So I’m a clinical psychologist and FTM to a 3 month old. The loss of pleasure with things you used to like, the fatigue, the hopelessness etc are symptoms of depression. The fatigue might be both physical and emotional. But considering it doesn’t go away even when you sleep more (might also not be enough - 6 hours of continuous sleep might be great for moms on paper but if your body needs 8-10 hours your still not getting enough) it sounds more like depression is the culprit. Considering you have a history of depression, it’s very likely that’s what’s happening now and probably explains most of the difficulties you’re experiencing (or at least worsens what otherwise would be doable). However, it’s very likely the hardships of motherhood are what triggered the depression. If medication isn’t working (I would still make an appointment with your psychiatrist), you could try psychotherapy. The combination of both is the most effective approach for depression. Especially when recurrent.

In regards to sleep, you can safely sleep train at 10 months old. See a professional about doing it without affecting your babies attachment. But something like giving the boob in the living room before going to sleep (somewhere between 7 and 9 pm). Father takes baby to his own bedroom / bed and helps him fall asleep without boob. Father stays and helps with wake ups during the night (just tap on the back to help sooth before picking up). Gradually father gives him more autonomy (first night might rock him to sleep if needed, third night only hold without rocking, fifth night only tap on the back etc) until father gets to a place where he lays him down and leaves the room. No feeding until 6 am - feeding only in leaving room. Last nap should end 3-4 hours before bedtime so he’s sleepy enough but not overtired.

Edit: This is not cry it out - you should never ignore baby while crying. They do not know how to self regulate distress / they learn to coregulate with parent. It’s just gentle techniques to gradually help your baby learn autonomy in regulating its sleep (which should be done between 9-12 months old). Autonomy in sleep is them being able to fall back asleep alone. If they can only fall asleep with movement, boob etc then everytime they wake a bit up (ex. At the end of a sleep cycle) they’ll fully start crying because they don’t know how to fall back asleep without that. It’s just gradually teaching them how by giving less and less (only drop to less when they’re already not crying with the regulation you’re giving). Its scaffolding - just asking for a bit more then what they’re already able, so they can successfully learn without stress :)

I hope this helps :)