Flexibility in Ballet?

When I first started Ballet I was 9 years old and extremely flexible. I could do the Chinese splits and everything. I took a break from Ballet for about a year and a half and I lost everything and I am now 16 years old, but I have been doing Ballet for 5 years already after the break. I can't do the Chinese splits anymore, but I'm getting more flexible, however I recently pulled a muscle while stretching for the chinese splits and it still hurts so I was wondering if I am too old and if it's impossible to get as flexible as Ballerinas such as Svetlana Zakharova