What's The Likeliness of Me Being Pregnant?

I'm 17. A little less than a month ago I got drunk with a guy. I gave him a ******** but he never came, and we had unprotected sex for literally a second before I decided I didn't want to anymore with the little judgement I had, and we stopped. Like he was in, and then he was out. Since then my period hasn't come. I believe it should have come about 2 weeks ago but my period tends to be very irregular and has come very late or skipped a few times before but not anytime in the past 6 months. I've taken 2 pregnancy tests that I bought at walmart. They were the walmart brand (Equate) and claimed to be 98% accurate. Both came out negative. The first one I don't think I did right, but the second I know I did perfect and followed all the steps. Despite the fact that I had two negative test results I'm still paranoid. I sometimes feel like my period may start soon like in my abdomen but it still hasn't. Other than that I've been peeing a normal amount. I don't really feel bloated or really abnormally tired. My breasts feel normal. I don't have any abnormal headaches or backaches. I just really need to be sure of what's going on as soon as possible... So let me know what you think? Thank you.