constantly sore boobs

Hey so I have grown 3 cup sizes in the last year and a half and I was on the Depo now I'm clean since December and my boobs are always sore and have been for quite some time. they grew a lot in those 7 months and I am wondering why they are sore so often. when I wear a bra I'm fine, otherwise they are sensitive. is it because they are bigger than before and so they are sore when I do not wear a bra, is that normal? would love some input. thank you