Cheer/gymnastics help please?

ok ... so ive been working for a while for a backhandspring ... i am psychially capable of doing it on my own ... and i do (i mean on the tramp) ... but in the beginning ... my spoter has to hold my shirt just until i just backwards ... idk but if she oest do that ... i feel like i dont know what to do. i know its all in my head ... but how do i get over this?! i have tumbling tmrw ... so lpealse help fast! thanks alll!