plan b

I had unprotected sex in October, but we didn't "finish". But I just got nervous and took plan b. I started to spot and it lasted for 3 days. I took plan b before my fertility cycle or ovulation even started. Ever since I didn't get my period. I'm 17 btw and my cycle has been regular and then it would turn irregular. Currently my cycle is irregular. Anyway I had protected sex last Sunday. It's November and I still didn't get my period yet. Also it's like day 50 something I think in my cycle and I still didn't get it yet. I don't know what do. Someone please help me I'm really desperate for help right now.