seek help or not
I think that help from family and friends is the first place to start. Or maybe a postpartum moms group? I agree that you could mention it to your care provider at the six week visit.
I've had some similar feelings, although I'm about nine months postpartum now and they started around 7 months, especially with the fears about my own death and baby. It seems like that's a big thing with postpartum mood issues, so you're not alone in that. I realized that I needed to be getting a lot more help and making sure to meet my own needs too. So reaching out and getting help from people I know really helped a lot. If you get more concerned about how you're feeling, you can always get professional help too.
A few things that really helped a lot were talking with other adults about my life and what was stressing me out (birth experience, things that had been building up since pregnancy). Taking a milky oats tincture really helped calm my nerves a lot (they had felt really raw, like I was way more jumpy and sensitive even to minor stresses like DS1 whining). The other really big thing was getting more sleep.
Hope that helps. It sounds like your situation is really challenging and it's a lot to cope with! It also sounds like you're a really strong mama.
After my last post, I was thinking about this again and I realized that I left out the most important part of what has helped me....
Feeling SAFE. Once I started to do anything and everything I could that made me feel safe and comforted, I was able to relax and get rest and start coming back into balance. Seriously, no matter how ridiculous it felt like at the time, I would do it. Crawling back into bed in the middle of the day, just letting myself cry when I needed to, asking for comforting touch from anyone who was around...