Hey, I've been through that feeling three times now. Just remember , this is a SHORT time in life! Your little girl will get huge before you know it and you'll have plenty of time to get that body back. For now, enjoy every second you have with your little girl while she's tiny. All the stages are awesome, but the tiny one is the one I miss the most.
The milk thing too - everybody is different. Just like dieting when you aren't breastfeeding, you can experiment to get the right amount of calories. In my experience (listen to me, I'm only 28 and I sound 40!) proper hydration is by far more important than calories. Play around with your calories a bit (nothing drastic, go slow) and you'll find the right amount that gives your little girl what she needs and still lets you slowly start shedding the baby weight. And as long as you are past your 6 weeks post partum checkup, there is no reason to not train. Once again, I can tell you are a smart lady and I know you wouldn't go overboard and train hard and not eat much. The reason they warn people not to restrict calories AT ALL is because some women would start just drinking slimfast. I had a doc (who was a bodybuilder lady) give me that advice after my son was born. Too bad I didn't follow it, I'd be lean by now! LOL!