Bigger nipples??

I think my nipples have gotten alittle bigger. I take my pill every single day on time, and my boyfriend and I use condoms every time I have sex (we also check them afterwards to make sure everything's good and it always is) because of that all I've been told a million times that it would be unlikely to be pregnant. But the past couple days my boobs have been so sore (I did a lot of exercise recently so that could be one thing, and also my periods not for another 2 weeks so it can't be that just yet.) and I'm just freaking out! I haven't had any other symptoms, and my period ended a couple weeks ago and I haven't seen any bleeding or "spotting". I just don't understand why my boobs are noticeably swollen and sore. I need opinions please!