Possible pregnancy with irregular period?

I haven’t had a period since July, and I believe I have borderline PCOS, but just undiagnosed. My boyfriend and I had unprotected sex yesterday and he ended up finishing inside of me. We took protective measures and got a Plan B immediately. Should I be fine after this? I know Plan B usually starts your period a little while after taking it, but since I have irregular periods, will my period even show up?