COULD I BE PREGNANT? please help 😖

I have been on the combination pill since April 2012. About 4-5 months ago I switched to the POP (progestin only pill). It dramatically changed my cycle, my periods, my symptoms, my pms, everything. I switched to POP because combination gave me migraines, nausea, and the hormone dosage was so strong that I would throw up the first active pill of every cycle after my period. 

Now, on October 22nd I was 3 days in on my period and had unprotected sex. He came inside me, and that was that. I was supposed to start my period this passed Wednesday, 11/16, and I had some light pink discharge 11/19 and light brown discharge 11/20.

I'm a little nervous because even though my periods are a bit irregular since starting my POP, eve is hardly EVER off/wrong about guess-timating my period dates. I'm hoping I'm just paranoid. I know it hasn't even been a full week since my projected start date, but damn I'm nervous. The POP birth control has much lower dosage of hormones and if you skip a pill, it is highly likely to become pregnant. I have skipped pills before  but not recently enough to affect this. Please help!!!