breastfeeding and weight loss

Is this true?
My baby is 1 week 2 days old. 
I started at 155lbs and got up to 188lbs.
I weighted myself today and I'm 170lbs. 
So I'm down 18. Which I know is good .
I thought I would have lost more by now bc i wasn't that big and my baby was 8lbs alone.
People say water weight but I'm not really swollen anymore. I really want to start excercise but I can't bc I had a c section.
I do breast feed so would that help?
I have noticed I'm losing 1-2lbs a day but not sure if that's bc I'm breast feeding or what...
I'm just curious.