I THINK I MIGHT BE PREGNANT! IM REALLY SCARED

Sydney
So me and my boyfriend were having sex 6 days ago and I am off my birth control pill but we were using condoms and non of them broke. I went down on him and he came in my mouth. Then he fixed his dick so he can put it in his pants he then started to finger me and we both realized that he had a little cum on his hand and we both freaked out. We went and got plan B and I took it that day. I was also two days away from getting my period. This was also the first month I was off my birth control pill in 7 months. The next day I was cramping so bad that I was crying. And no period. The next day I was cramping even worse and still no period. The day I was suppose to get my period I wasn't cramping that much and still no period. It's been 4 days after I should have gotten my period. And I'm really scared. Is this because of the plan B and me getting off my birth control pills. Should I also take a pregnancy test? And should I just go back on my birth control right away so I can get my period?