I need some advice

I've been with my significant other almost 3 years. We've never used condoms & always had pulled out. I had also been on birth control since last December. When I came off birth control, he still pulled out, then in April, we decided to stop pulling out. July- December I was gone doing training for the army. So my question is "is it normal so to speak that we haven't gotten pregnant by accident yet for as long as we've been together and doing the pull out method then the couple months where it wasnt lined up with my ovulation when we didn't pull out....?" I just am already scared when I think of the what if we can't conceive thing. It breaks my heart. Any advice would be so great.