hi

i'm 17 and for some reason i seem to be unable to have sex (i'm a girl btw).
i tried once last year and me and the guy couldnt do it, he just like, wouldnt go in, i assumed it was because i was kinda repulsed by him so wasn't turned on or something.
but i tried again twice with my boyfriend of 7 months and same thing happened.
i don't know why, had plenty of foreplay and it all went fine.

i'm starting to really worry about it.

does anybody have any idea why this is happening or how i can fix it?