Your body changes a lot during pregnancy and while you are nursing. Your body can look a lot different right before you get your first PPAF. This last time, I could feel mine coming for almost two months. I was taking a pregnancy test every week because I felt so pregnant. I knew I wasn't, but my body sure fooled me. I felt bloated, irritable, a little queasy, tired, and crampy. My boobs got bigger.
Is it possible that you are seeing so many changes, in part, because you are looking so hard? Many women notice prominent veins on their breasts right before they get their period. The premenstrual period seems to be longer for women who are nursing. This could just be a normal reaction to your body gearing up to ovulate and/or menstruate again.
Regardless, I really think you should see a health care provider to put your mind at ease about all of this. Maybe after speaking to someone on Monday you will feel more relaxed.