sore nipples

Courtney • TTC our 🌈
So I'm not sure where to post this so I thought I should post it here. 
I have sore nipples and almost like a burn when they're rubbed against something. And my breasts feel fuller. 
Not sure what's going on. 
Yes I've had unprotected sex and multiple times around my fertile days. But not 100% sure on when I'm supposed to get my next period due to them being irregular. 
If someone could give me some insight on this that would be awesome. Thank you.