Very confused!

We only had sex on the 19th which was 3 days before my period was suppose to come. I’ve always been regular in terms of getting my period when I’m suppose to, even after giving birth to my first. I am currently 4 days late and still having loads of discharge down south (which is abnormal) and it’s reminded me of thick mucus from pregnancy. I took a early result wondfo this morning and don’t see anything! I’m so confused!