What Causes Swollen And Heavy Breast, Green Prominent Veins And Dark Nipples?

hi i take the mini pill noriday and take it every day for the last 3 months i dont have periods and have not for over a year due to contraception, for the last 3 weeks my boobs have become swollen and heavy and the areolas have become swollen with green veins that are prominant, also my nipples have gone darker and montgomery glands are more visible, is this due to hormones or could i be pregnant