Withdrawal method + birth control pill

I have been on the pill since January of this year and have not missed a single pill. A few times I’ve taken it an hour or so late, but I would say that I use it perfectly. My boyfriend and I have been sexually active together almost always using condoms. This month, however, we didn’t have one on us and decided to go without one. We are very, very careful with this stuff, so he pulled out way before he had to finish. We had sex, he pulled out, we waited like 3 seconds, and then he started to finish away from me. Of course I’m a hypochondriac and 2 weeks later I am starting to feel abnormal cramping, but I’m not sure if it’s just in my head. I read somewhere that when used together, withdrawal and the pill are 99.8% effective. I just want some opinions on if I’m safe from pregnancy, or if anyone knows someone who has gotten pregnant in this type of situation. Thanks!