Maybe pregnant?

This month I lost my birth control pills, I believe my sister accidentally threw them away. I took the first few days but I haven’t been taking birth control since. The last two days my left nipple has been increasingly sore and sensitive and looks larger than usual. I wouldn’t call it swollen it just looks larger and is so sore it hurts. My right one is a little bigger than normal as well but not nearly as sensitive and only sore to the touch. I took a pregnancy test last night and one this morning and both came out as negative. Could this all be a reaction to not being on the pill for so long? Or could this be an early sign of pregnancy? I’ve looked up symptoms and it keeps coming up as an early sign of pregnancy or mastitis and my OBGYN is not open until Monday or I would just make an appointment. I hadn’t had sex for about almost two weeks now and I believe I got off of my last period right before Christmas but it’s just a guess because I honestly do not even remember when it last was. Anyone else ever go though this before or know what it could be? I am 21 if that makes a difference or not.