I was like that after having both of my kiddos. It was just because I hadn't slept much before giving birth so I was tired all the time. It got better after a while though. I had to remember to drink a lot of water and to eat three meals a day but since I was breastfeeding I had to eat more. I usually just snacked on things.

You might have low iron or something? Are you eating enough? That kinda worries me.