Scaring my self....

First of all I’m on the Pill, and have been for over two years. Well my left boob is so sore thing month and my right one isn’t..

now if I’m thinking correctly then this happens every month. But I can’t help but make myself think something is wrong. I’m only 19 years, and im actually stopping the pill at the end of this month. Do y’all think it’s probably just my birth control causing it? Should I tell my OBGYN, When I go in?? (Please no hate)