You may have gain some weight recently, so, you find your breasts larger.
Although, you had menstrual bleeding, still, test for pregnancy.
If you have changed your diet, you may added some foods that are source of phytoestrogen (flex seeds, tofu, soy yogurt, soy beans), estrogen found in plants, that usually gives breast enlargement as a effect.
This breast enlargement can be, also, a side effect of using birth control pills.