Nursing and getting fit

Hi! I am breastfeeding mom (pumping while at work) with a 4 month old daughter. Started counting calories about a week ago to shed the baby weight, 30 pounds to lose to get to pre-baby weight and an additional 10 to lose to get to goal. I allowed myself 2000 calories but my supply still tanked in the one week I was counting and despite alot of lean protein, fruits, and veggies I was STARVING. I had been pumping 18 ounces a day with 4 sessions a day and it went down to less than 10 when I started counting my calories. And of course my luck would be that I also didn't lose any weight during that week. I'm super jealous of the ladies whose weight melts off during breastfeeding, that is def not the case for me! My daughters pediatrician recommended shooting for 2300 calories and see where that brought me. I've been doing that this week in addition to a lactate support supplement and a ton of water, which seems to bring up my supply a little. I'm worried that my weight loss efforts will have to wait until my baby weans. Any advice? I will also add that my daughter has a slight dairy protein intolerance so I have eliminated obvious dairy from my diet.