Is pregnancy possible? I’m terrified.

So I’ve been on the pill for 1.5 years. 5/6 days before my withdrawal bleed I had unprotected Sex with my boyfriend but he did not finish in me. I usually have a day or two of spotting before my bleed, well, my bleed is due today and I have had NOTHING. no blood, no discharge, only small quick cramps here and there. This is so weird. I’ve had a slight headache for the past two days. I also have been through a little emotional stress ( lots of crying) in the past week, not sure if stress counts on the pill. I’m scared. Help?