Sudden Breast Growth/Tenderness

Hello..... Within the last week or so I have noticed my breasts have gotten bigger in size. I had small breasts after breastfeeding my daughter, (I stopped bf a year ago) and I had to buy new bras cause of my size difference I wear a 36A and now my breasts are trying to come out. I'm not sure why. I am not pregnant. I am on Nexplanon birth control and we use condoms. I just think its strange... Should I be worried???