I want to do the splits?

Right, i can nearly do the split but when i go down, my body leans to the left side of me. I want to sit up like gymnasts do and i want to go down into the split. My family won't push me down because they think i will tear my muscle. I go to gymnastics and trampolining on mon, tues, thurs, sat and sun but i still can't do it. Please help and give me some tips please. Also what are some good stretches which can improve your flexibility? Thanks, Rosie