Hello, I haven't had a period in over a month and a half. I am sexually active and my boyfriend always uses the pull out method. I know that it's not the best method and you can still get pregnant from it. I've taken 4 HPTs and they all came back negative. My doctor didn't give me a blood test though because apparently they don't do that anymore. I have regular periods for the most part. It will be late sometimes but I never skip one. I've been having some symptoms of pregnancy but not a lot. So I was just wondering, could I still be pregnant even though the tests came back negative? I also was wondering what is causing my period to be missing if it's not pregnancy. I'm underweight but that hasn't affected it before and I haven't changed my habits recently. Oh and I was going to start birth control tomorrow. Is that safe to do even with a chance of pregnancy?