PP depression or just emotional

I wouldn't normally consider myself an emotional person but ever since I've had my son, 6 weeks ago, I cry whenever I'm alone. Not everyday & I'm fine when I'm around other people though. I can't eat. I eat maybe once a day if that and I crave alcohol so bad.. stopped drinking 2 years ago because it started to consume my life and effect my personal relationships. I don't think about hurting myself but I catch myself thinking about how my fiance would feel if I was gone and if he'd even care. He works a long distant job and isn't home on weekends and I'm scared to death to be by myself with my son. I think of the craziest scenarios of someone breaking in and what they would do to us. My dad mentioned a gun since we are alone and was showing me some options and started shooting and I had a panic attack. People have mentioned PP depression to me, I guess because of weird things I have said and now I question it too.