Moms with two kids...

I am 3 weeks postpartum and I have a daughter who just turned 4 years old. I’ve noticed since I came home from the hospital I don’t feel as close to my oldest as I used to. I snap at her, get frustrated when she doesn’t listen, feel like the bond we shared is not what it was. Don’t get me wrong, I love her so much and would do anything for her. But I feel like my patience with her is thin and that the closeness we had isn’t there anymore. I’m not sure if this is normal or some possible postpartum depression of some sort? I feel so bad and want to cry because it’s not fair to her. It makes me feel like a crappy mom.