I started the pill on Sunday, then took it Sun-Wed. I forgot to take it Thurs-Sat and my boyfriend came in me on Friday. Then today (Mon) I was spotting. Is it because of implantation or because I missed my pills? Am I pregnant?

It's probably because you missed some pills. However pregnancy is always a possibility. It would be too early for any symptoms such as implantation bleeding since today is only Monday. You will have to wait to see if your next period comes as expected.