Could I possibly be pregnant?

Hi everyone.
I'd like to know if there's a chance I could be pregnant, and here's why.
I had my period from December 6th to December 12th. On the 13th, I had unprotected sex with my partner, but about a week later I got really bad breast pain/sensitivity, and when I pressed on my nipple some fluid came out. Also, I've been extremely tired for the past 4 days, staying in bed all day.
I also have a lot of thick white discharge (thick like milk, just no smell, neutral).
And I can't lie on my stomach because it hurts, and even when I lie on my side it hurts. It can't be my period because I'm not supposed to get my period until January 6th.

Could you give me some tips or your opinion?