4days ago i noticed bright blue veins on my breasts but i do have large breasts and on depo-provera shot but why are they suddenly popping up

Change in pressure : There is probably increased venous pressure. See your doctor to make sure there is nothing else causing this problem.

Breast Veins: It is not uncommon to have blue veins on the breasts and usually this is a normal finding. Many factors can contribute to this including hormonal therapy, genetics and aging . Blue breasts veins can be easily treated by sclerotherapy. See a vein specialist. Some one with experience treating breasts veins can advise you if an additional testing is necessary.