Question about conception/implantation..?

My fiance` and I had intercourse a few nights ago, unprotected, and I let him ejaculate inside of me. I have been ovulating. We are okay with the idea of having a baby, but we haven't been just TTC. I have been on BC for some time now but have been on antibiotics the past week or so which renders it virtually ineffective. I have heard of other women having implantation cramps, and today I have been having cramps similar to period cramps. I know some women have cramps when they ovulate, but I never have. I also couldn't be starting my period because it's not time, yet. Also today, I have been feeling slightly dizzy at random. I was wondering if anyone else who has found out they're pregnant have had similar experiences or can offer any advice?