How do I get passed this?

I was raised in a household where sex was shunned and taught to be associated with pain. I'm 20, my partner is 23 & I'd love to be able to do...anything involving penetration but I freak out. It isn't that I'm uncomfortable with him. It's like a mental thing with me. I'd like to get on birth control soon I think that may help, but fingering even freaks me out. What can I do? I do have a disability and I believe the difficulties with that may be part of it