plan b

So I had unprotected sex in October on Saturday with my bf. But we didn't finish but  I decided to take plan b the next day. I believe that this happened before my fertility cycle even started. Yeah it was definitely before my fertility cycle started. I began to get cramps right away but it went away in like 5 mins. Then a couple of days I started to bleed. It was light at first and then it was moderate. The bleeding lasted for 3 days. I do have an irregular cycle. Usually I do get it every month but sometimes I do skip from working out or just stress. Last Sunday I had protected sex. I still didn't get my period yet. It's day 51 for my cycle and I still didn't get my period yet btw i'm 17. I don't know what to do. Can anyone please help me?