Pregnant or not

Hey guys..I’m 19 years old. For almost a year now I’ve been on the Aubra Birth control, I’ve had no pregnancy scares whatsoever until now. So last month , during the time I was supposed to get my period, I was bleeding..but SUPER LIGHT, I mean not even enough to fill up 3 pads. It lasted almost 3 days. I always take my pills on time. I went to a clinic and got a test which came out negative, they told me it could just be side effects from the birth control. But lately I’ve been feeling so different. Headaches, nausea, I’ve been feeling SUPER bloated, and my boobs have drastically changed. Since the test at the health clinic I’ve taken 3 other tests that have all came out negative. Has anyone else felt this way? Should I be concerned? My period is supposed to come in 4 days, and It’s just making me sick thinking that I could be pregnant . Help