My right breast is swollen?

Yeah. Just the right one. It was really tender earlier this week, but not so much now. I'm due to get my period in the next couple of days.

There's a very, very slim chance i'm pregnant (but my BC is 99.1% effective + condom, so...)

My breasts usually get sore before my period, but they've never swollen. I swear, I've increased a cup size, and it's just on the right. This is so awkward.

Any advice?