Advice ?plz

So I had unprotected sex with my boyfriend on a Monday(9/10/18)I took plan b after 2 hours of having unprotected sex with him. A week later I think I got my period , lasted for 4-5 days , I felt like it was a short period of time because normally my period is 5-6 days. The first day that it started I cramped a lot , It hurt sooo much. The rest of the days felt as if I’m not even on my period. I just ended it like 2 days ago but I’m spotting right after I just ended it 2 days ago & had protected sex with him again on Saturday(9/15/18). Then today ( 10/03/18) we were in the car & he started fingering me. I came home & I wiped my self & there was blood. Not a lot just as if it’s spotting. I think I’m pregnant but I don’t think I am because I started my period a week after I took plan b. Can someone give me advice ?