My boyfriend’s dick is too big.

I know it sounds stupid at first, but my boyfriend’s dick is genuinely too long. Having sex in most positions hurts too much as I can feel his penis hitting my cervix, and then I am left with stomach cramps after sex. We both are aware of it, but there is only so much we know to do… we know usually only have sex in doggy as that is the least painful.

Does anyone have any advice they can give? I really would love to enjoy missionary and other positions, but i feel like I am being prodded into my stomach everytime

Edit: Guys i did not expect the comments to be so hilariously informative. Thank you all for all the advice. For some questions that have been asked: he is 8 inches, we do like rough sex, but even with the gentle kind it still hurts. I also am allergic to semen, so after the first round he cannot even re-enter the playground. And a reply also mentioned their partner having endometriosis, and I should probably check that out because it does run in my family

EXTRA EDIT: a lot of the guys in the comments are saying that they are now satisfies with their “smaller/average” size.. MEN, please dont be ashamed or feel like your size is not enough! A 4 inch can feel as good or even better than an eggplant sized penis, it is mostly about confidence, and how you use it, and not the actual size.