I am an outstanding teacher. I'm one of those meant to be thoroughly able to weather the storm of constant change to the education system. If you believe much of the media, the 40% of teachers who leave the profession in their first five years are failing as the coalition's education policies pick off the weak and the lazy from the back of the herd. Yet, here I am, a 30-year-old outstanding teacher, and I've just left the profession.

According to all the different criteria against which I have been judged, despite the constant shifting of goalposts, I have been outstanding. I worked hard; I delivered engaging yet academically challenging lessons – despite us all being told that these two concepts were mutually exclusive; I assessed pupils in rigorous detail against ever-changing marking schemes; I completed fatuous administrative tasks within all deadlines. I was at the top of my game. I should have been seeking promotion opportunities. Instead I found myself, along with my pupils, becoming increasingly insignificant. Now the school to which I gave my twenties is haemorrhaging good and outstanding teachers.

I never foresaw the problems which would eventually drive me out of the profession. I went into teaching believing that I was the kind of person that the government would want to teach young people. My background was not at all affluent. I worked hard, got a good degree in English Literature from a redbrick university, and chose a teaching career. I steeled myself for hard work, though of course I didn't realise I would be averaging 60-70 hours a week – even when I opted to reduce my pay by going part-time (an exercise in self-preservation that failed).

I taught everyone well. From the most able, who went on to study at some of the most elite and selective universities in the world, to those who could barely form a sentence.

While trying to teach young people, I attempted to gain their interest and meet their individual needs. This is the point at which my educational philosophies diverge irreparably from those of the government: I see children as individuals; today's ministers see them as a mass that must be trained.

This became particularly visible in Michael Gove's reforms to the English Literature curriculum, which come into effect next month even though he is now out of the picture. Gove was unable to relate to anyone or any belief system outside of his very narrow range of experience, and yet, due to his changes, all young people in Britain (regardless of gender, ethnicity, class, or individuality) are now expected to relate to the white, middle-aged, upper-middle class values which he decided were the right values. There is, apparently, no literary merit in any writer beyond these boundaries.

This intellectual snobbery would have made my job not only impossible, but also soul destroying. I cannot stand at the front of a classroom and make children chant the works of Keats – instilling in them the belief that the only voices worth hearing in our society are those of a dead, white, English, male establishment figure.

I also cannot work in a system that prioritises political gain over the good of our young people. This was exemplified in September 2013, when it was decided that league tables should reflect the results of pupils' first attempt at an exam. Interestingly, this was announced in the same week as industrial strike action: let's try not to be too cynical about that. Still, implementing the change with immediate effect, weeks before students were due to sit their GCSEs, was a particularly repulsive action. Against my better judgment, I actually agreed that the resit culture was not beneficial to teachers or pupils. But yet again it was the children who suffered the fallout of a politically motivated decision. They had worked hard to meet the rules of the game that they were playing, then those rules were changed. We were put in the position, by our government, where we had to choose between pupils and league tables: we let them sit their exam. We never should have been put in that position. I can't face any more reckless decisions like this, in which politicians don't think about the children involved.

It is galling to come home from a 12-hour day at work, to turn on the news only to be told that I "must work harder", that we are failing pupils, that we are not keeping pace with the world. The public, throughout the years of the coalition government, has been empowered to distrust teachers. But it is this government that has failed pupils.

This is then reflected in our school structures. School leaders are in fear of the next decision that might be wreaked upon our schools. They have been informed that this country's teachers are failing, and that they must take charge of a lazy and unprofessional teaching staff, leading to suspicion within our schools. Let me reiterate: I was good at my job, I worked long hours, and yet how much of this mattered? Like many teachers I know, I often found that by 9:30am (by which point I had been at school for two hours) I felt I had been reprimanded five or six times in emails to all staff, or in departmental meetings, or staff briefings – all a direct result of current education policies.

Rebukes tended to focus on the looming threats of Ofsted at the start of the year, constant reminders of why we did not achieve "Outstanding" once Ofsted had been, insufficient use of pupil premium data, and expecting more admin tasks to be completed within lessons. We felt a failure if we didn't manage this alongside our teaching load and were told off if we couldn't provide evidence for what we were doing. At one point, we were told that helping pupils outside of lessons was not "measurable" and we should use our time on things that were.

Real change happens in the classroom, but the constant criticism means the hearts and minds of teachers have been lost. As we move towards increasing numbers of academies and free schools, this problem can only worsen, as it rests upon a central misunderstanding of what actually happens in schools. It is beginning to cost the education system dearly, and my concern is that the damage inflicted upon it will be enduring.

I must admit, when I found out that Gove had been "reshuffled" (in the final week of my seven-year teaching career) I had a moment's doubt. Was my decision the wrong one? The regret did not last long. My plan to move to France and run a ski chalet with my husband (another disaffected teacher) was not only carefully considered, but also necessary. The damage to education has been done and will take a long time to fix.

We now have a generation of pupils who have been trained that their individual opinions and skills are invalid, that reading is only worthwhile if the text was written by a white, British man; we have a generation of disaffected teachers, who are woeful about the notion of change (even if it's sometimes for the better); and a generation of school leaders that has been told that managing teachers must involve distrusting them. Politicians may be transient, but attitudes are not. The rot has set in, its effects will be felt for years.