I like to imagine by their heights and voices that ember is likely just 2 or 3 yrs older then spike. Its also possible they could be close to the same age but like with some human being the girls grow faster when young. Like how some 12 yr old human girls can stand taller then guys their age or a year younger but within a year or 2 after that the boys shoot up and tower taller. Given a year or 2 he might be as tall as garble while ember just shots up 3 inches.

That stuff aside I really did love her character and we got to finally see their Earth from the dragons point of view. I hope before everything is said and done for G4 we get to see their whole worlds and the creatures with random customs in it before they get to G5 in who knows how many years.