Inserting Fingers

I can’t insert my fingers when I masterbate. It hurts so much. I don’t even feel pleasure I’m a virgin and I’m lesbian. I’ve never even put a tampon in but my girlfriend can put two fingers in with no struggle is it just that I’m too tight? Or I’m not wet enough? Am I doing something wrong? My sex drive has also been really low could that be Bc I’m on anti depressants? Please help!! I want to be able to have an orgasm from something other than clit stimulation.