Suicidal/Post Partum Depression

I just had my baby in Sept. I love her to death. But I’m constantly thinking about suicide or just up and leaving but I could never do either. I don’t know if it’s suppose to be this hard with a newborn since this is my first child. She cries constantly and my milk supply has went to shit, I don’t eat but maybe once a day, I’ve started smoking pot again just so I don’t have to feel anything, I’m exhausted mentally, emotionally, and physically. my fiancé doesn’t exactly know how I’m feeling because I can’t open up the way I want to. I’m scared to ask for help because I don’t know what will happen or if maybe I’m just being irrational. I hate it because I have a hard time just trying to figure out the way I’m feeling when I just feel so many things at once. I know none of this makes sense but what I’m really getting at is if anyone else has felt this way? Did you get help? How did you get help? Should I just wait it out and see how I feel in a few months?