Sore Breats

So my period ended on the 1st. I had sex 2-3 days after it ended.

I noticed around the 9th that my boobs felt very sore, heavy, swollen... I tested on the 11th, which I’m aware was very early. It was negative. I retested on the 14th, still came back negative. My period isn’t due again for a bit over a week. I have no clue what’s going on. My boobs never ache like this until like the week my period is due so for it to start hurting just a week after my period ended & still, seems so odd to me.