Breast engorgement at 7 weeks

The past week my boobs have gotten so big and they are quite uncomfortable. I haven't breast fed my son since he was 4 months and he'll be 2 November 7th. I'm just confused to why they are getting so big & uncomfortable so soon. I'm not exactly sure how far along I am my appointment isn't until Halloween but I think I'm around 6 or 7 weeks.