Stressed. Pain during deep penetration.

Kaitlin • Wife to SB. Mommy to PB.
Hi guys, this is my first month TTC. For about a year now when my husband goes deep during sex. I feel pain. It's pretty intense. It's almost like he is hitting something up inside me. I was diagnosed with IC, a bladder issue that is said to cause painful sex but honestly I wrote it off for a while because I never had pain when I had to pee. Which is supposed to be the big issue. I just pee very often and then I have the sex pain. I'm worried something could be wrong since it hurts. It doesn't hurt in every position. Mainly just doggy and when he spreads my legs really wide. Abu insights on this? I would appreciate any kind of guidance since it's become the only thing I can worry about lately. Which I know isn't good when TTC. It only hurts when he goes really deep. I've had my annual exams and I've never heard anything, I cramp on the first day of my period (not before, just the 1st day) - it sucks but midol usually takes care of it. Advice or any insight is wanted :(