Postpartum depression..

So I know there are many levels to this and that it can go from slight to major really fast. Let me start off by saying I love my child more than anything in the world I have never ever thought of hurting him on purpose. However, at night sometimes I get so ridiculously angry at him for waking up.. Not very often maybe 4-5 times in the last 3 weeks since I had him. And all of these times I had either just fallen asleep or I have had a migraine I needed sleep to help get rid of. And lately I'm so terrified I'm going to lose my baby, terrified that I'm going to miss a sign of something being wrong and he's gonna die. I don't want to think like this and my best friend suggested I look into therapy to help me cope with this feeling. My baby boy has a hematoma on his head from birth it was really soft and today it's hard so I've convinced myself he's gonna die. Even though my pediatrician told me to just make an appointment on Monday that it's not an urgent matter. I know I'm not the only first time mom who feels like she's going bat shit crazy.. Someone please talk to me..