Period while Breastfeeding!

So my son is now 7 weeks old and exclusively BF. New years eve I went to the restroom bc it felt like I was wet downstairs. Turns out it was blood! It was very minimal but it was red and brown. The next morning I went to the bathroom and sure enough it was AF! I'm so disappointed it came back this fast. I thought I wouldn't have it until much later as my lactation consultant told me I probably wouldn't get it this soon. Did anyone else have their AF back this early and does it affect milk supply? BTW I stopped bleeding at 4 weeks. Is this normal or could it be late bleeding?