Sex WTF

Alright so I’m 17 and I haven’t had sex and me and my kinda boyfriend (long story) have tried to have sex like three times. The first tome it was just kinda weird and gross so I didn’t want to. Which I know is fine and he was a gentleman about it. But when we’ve tried it hurt so much. Like he wasn’t even in but the pain was honestly unbearable like ew how do people yea aha so I’m just REALLY FUCKING tight down there and my sister just said live but I feel like there’s something wrong with me. Am I doing something wrong like is it me.

Also I have to be on top coz it literally hurts his back to be on (no he’s not an old man, problems since he was a kid) and it’s kinda annoying and sucks because I have no clue what I’m doing x