I have friends that do WW while nursing, these are the same that would use it not-nursing also. For myself, WW is just not my thing.
It sounds counter-intuitive, but the most important thing for me to remember is to eat ENOUGH. If I cut back too much, my body will not let me lose weight, even though I have plenty to lose. also I try to do some moderate activity every day. The weight is coming off slowly, but the number on the scale is going DOWN! yay! I am 6 months PP now and have breastfed the whole time, and I have lost 28 lbs - which is 3 more than I gained while pregnant. I have a long way to go yet before a truly "healthy" weight, but I think slow and steady will win it.
I only notice a slight drop in supply during my period, which is completely normal. it returned at 4 months PP. I think just as important as calories is drinking enough fluids. You can always consider adding fenugreek or a mother's milk tea to help boost supply.