I had protected intercourse and I took the ipill, and there is no period

Hi,Had protected sex on 28 sep,then took ipill after 50hrs,i suppose to have period by 12th oct, got on 16 oct.it was normal flow and stayed 4 days,then after i haven't got period.On 24th i found 2 drop on my panty, we had protected sex and took ipill also and i had 4 days normal period also. but this month i mean for nov i didn't got. I am in tense. Am i pregnant ? Note: My periods are irregular always.