I don’t know if I am pregnant or not

I had sex with a guy and it was really good. He asked if he could bust inside me. I said yes cause I was on birth control. (I have been on birth control for 3 months but then I changed them to a different brand so I was on a new pack of pills). I had just finished my period and I started to bleed a little after we finished. Then after he left I looked on my phone and realized I am on my fertile time. And then a few days later I threw up and the next day I think I have spotting. Am I pregnant or are these just symptoms of a new birth control?

(I had really bad side effects on my old birth control so that’s why I switched). Could this be the same thing, just side effects?