pregnant? help

Bella
I started birth control a week before my period which was the 13th of November and my period began the 20th of November. After my period was over (two weeks after starting birth control) I started to have unprotected sex and have been since. I haven't started my period yet and today is the 24th of December(merry xmas <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">eve</a> y'all) I almost always get my period around the 19-20 of the month. I noticed my last period in November was longer than usual, about 3-4 days longer of old blood so I am thinking I just need to wait longer since the last one ended late maybe this one will start late. Or maybe birth control is messing with my body. I took a pregnancy test yesterday(three days after my missed period) I took the first response test, the ones that are supposed to be able to determine pregnancy 6 days before your missed period and it was negative. I think I'm paranoid but I don't take my birth control at the exact same time everyday sometimes I'm 2 hours late. One time I was 4 hours late but that was once. But that one time is what is making me paranoid. Help.