Am I Pregnant?

I’m afraid I may be pregnant. I am seventeen with a boyfriend of almost 5 months. We love each other very much. I’ve been on birth control since we’ve been together. I frequently forget to take my pill because I get side tracked very easily. Usually, if I forgot to take a pill and am spotty with it I will have breakthrough bleeding. I have had a lot of unusual break through bleeding along with my period, so bleeding is almost constant. Since I was on my actual period, my boyfriend and I decided it would be okay for him to completely do the deed and I even took plan B immediately afterwords. That was a month ago, and I haven’t had any break through bleeding and I am late for my period, which was supposed to start a week ago. I’ve taken two tests, both negative. I’m showing signs of early pregnancy though. Can someone please give me their opinion on what they think is happening to me?