Image caption Ryan has post-traumatic stress disorder, anxiety and attachment issues

"Last night he was kicking us, hitting us, thumping, spitting," says Diane, mother of nine-year-old Ryan. "Every swear word in the book came out."

Ryan was adopted at age three after two years in foster care after he was removed from his abusive family home.

Diane says his behaviour is him "trying to cope with what's been done to him".

But their experience is not uncommon, with 65% of parents surveyed by Adoption UK saying their child had been aggressive or violent towards them.

Diane is one of 3,500 families interviewed by the charity for its first comprehensive "stock-take" of the experiences of adoptive families and their children across the UK in a single year (2018).

The charity's Adoption Barometer finds that 56% of established adoptive families are facing significant or extreme challenges and 70% feel it is a continual struggle to get the help and support their child needs.

Furthermore, 80% of respondents felt their child needed more support in school than their peers.

Diane says she has not felt properly supported in helping Ryan with his post-traumatic stress disorder, anxiety and attachment issues - and even lodged a complaint against her local authority.

"We seem to have to fight for everything," she told BBC News.

"Nobody really cares, it's like, 'You adopted these kids, you knew it wouldn't be straightforward,' but I don't think we were warned enough about the issues.

"We're just left to deal with it, because no-one's got the answer.

"These kids have been through hell and we need to help them come to terms with what's happened.

Image caption Diane says she has no regrets and will keep fighting for Ryan

"These children have done nothing wrong - it's other people's fault, it's them who have caused their issues and yet they're the ones left to cope with it all."

There are about 55,000 adoptive families in the UK. More than 4,500 children were adopted in the UK during the year ending March 2018.

Adoption UK says most adopted children will have experienced abuse or neglect.

The charity's report suggests 39% of adopted 16- to 25-year-olds were involved with mental health services during 2018.

And nearly three-quarters of parents of adopted 16- to 25-year-olds surveyed by Adoption UK said they would need "significant ongoing support" to live independently.

Getty Adoption: Key statistics 65%of parents experienced aggression from their child 27% of new adopters wanted more information about their child

70% struggle to get the help and support their child needs

79%would encourage others to consider adoption Source: Adoption UK

Report author Becky Brooks said: "These are strong and optimistic families, improving the life chances of some of the UK's most complex and vulnerable children.

"But for too many families, getting support to help their children overcome their tough start in life is like fighting a losing battle."

Minister for Children and Families Nadhim Zahawi said adopted children were given top priority in school admissions and benefited from the support of designated teachers and pupil premium funding.

"We also invested £120m in the Adoption Support Fund which provides therapeutic support to adoptive families from the point at which the child is placed with them," he said.

Most of the adoptive parents surveyed remained optimistic about their family's future, however, and 79% said they would encourage others to consider adoption.

Despite all the difficulties, Diane says, she and her husband have no regrets about adopting Ryan.

"In the bleakest times you wonder, 'Did we get this right?' Yes, totally. He's got us to fight for him now.

"He's my cub and I'm his lioness and I will fight for him, because he deserves it.

"It's not his fault - he was just born to the wrong family."

Names have been changed by Adoption UK to protect Diane and her family.