Crazy periods and birth control is this normal?

So ever since I got my period back from after giving birth it has been really irregular. For the first 3 months I would get it 2 times that month. In July though I started taking a new birth control pill on the first day of my cycle. That period lasted for 9 days then I got it again a couple days later for about 3 days it stoped for 2 days and then I started bleeding again it finally stopped but it started back up yesterday. I feel like I’ve been on my period forever. Also I don’t know if it’s just cause I’m paranoid but I have been throwing up and nauseous and have had heart burn and even feel occasional flickers in my lower belly I have took many pregnancy tests and are all negative and doubt that I’m pregnant since I’m bleeding I think it’s just all in my head. Do you think it’s the birth control that’s making me feel sick and bleed so much?