Should I take a fertility test?

Me and my boyfriend have been together for 4 years, there have been times we haven't been as careful during sex, I was on and off birth control, now we are being very careful because I don't want to get pregnant at this time. Even though we don't want kids right now I'm kind of suprised I didn't end up pregnant during the times we weren't careful (it was always a heat of the moment thing). I'm worried I might have fertility issues. I was born with precocious puberty so my body develops faster than it should (i started puberty in 1st grade) and I create more hormones than normal. Even if I'm not ready for kids would it be crazy to check my fertility? I probably could have just gotten lucky but I always have that fear in the back of my head.