Need advice.

Hi so I'm wondering if anyone can help me out with what's going on with my period lately. I've been dating the same person for five years now, and we love each other both very much however we really do not want to have a baby at the moment. I've been on birth control for over year, i was experiencing many Moodswings during that time. So I decided it was best to stop taking birth control for A month to get my hormones back to normal. After being off birth control for a month we realized condoms just werent an option anymore and I needed to get back on the pill. During that time I was not on the pill, we did have unprotected sex but he always pulled out.I am currently back on the pill and have been for a month. However I am starting to get concerned because my period came before the normal time this monthand it has lasted a lot longer than normal. Usually my period is heavy in the first two days, and then slightly gets lighter and ends in spotting. My period is heavy and has lasted longer than seven days now. I have experienced blood clots and lots of cramping, and I'm wondering if I can possibly be pregnant. Even though I'm on the pill again, I was put on antibiotics for a sinus infection and he still came inside of me. I told him not to, because I know antibiotics can alter your birth control, but he clearly forgot. I recently took a pregnancy test and it came back negative, I am just wondering if I took it too soon. The bleeding has not stopped yet and I have been getting very bad headaches and feeling kinda sick the past two weeks. Does this have something to do with my hormones being changed from starting the pill again? Or is there a chance that I really could be pregnant? Or could this be a miscarriage?