Struggling to have sex

I’ve been really struggling to have sex with my partner for months now and it’s starting to really affect our relationship. My boyfriend feels unwanted.

I can’t seem to get in the mood and I’m too in my head and overthinking to have sex with him. It’s only been the past few months and it really stresses me out and makes me anxious knowing I’m not satisfying my partner.

He says it’s okay but I can tell it’s bothering him. I was sexually assaulted a few years back by an ex partner and I’m worried it’s unresolved trauma coming back. Or it could simply be my birth control. I just want to be able to be intimate with my partner. What do I do?