Could I be pregnant? Please help!

So I had unprotected sex with my boyfriend on the 22/03/19. This was my first time and we had sex 3 times within the space of 2hours, and all three times he came in me (sorry TMI). This was 19 days post my last period which ended on 02/03/19. I don’t know my exact cycle I never tracked it before. But I believe I was due again around 31/03/19. 3 days after sex I started bleeding. I thought this was my period and it could be, but it was so irregular. The first 2 days was really heavy like a normal period and the next 3 days it was so very light and I would have a mixture of bright red and brown blood. During this ‘period’ I was feeling tired, I had unusual headaches that I never had and light cramping. (I read that some women have had heavy implantation bleeding). And since then I’ve been bloated a lot, heavy tender breast. Past 3 days I’ve been really bloated, feel gassy and very slightly sick. I think it was 6 or 7 days post the bleeding I took a digital hpt and I got a negative. Before this I took about 3 and I got all negatives (it was way too early to take a hpt then). I haven’t taken one since because I’m not sure what to expect. Sometimes I feel like I get phantom symptoms because I keep thinking I’m pregnant. I would like your thoughts on this. Literally racking my brain over this!