Exhaustion is hitting different

I had my first baby at 18. It was a breeze. We had issues but it was not exhausting. Second baby at 24 and being pregnant was hard. I didn't get to experience life with him because he was still born. Next child was born when I was 25. I was so worried she wouldn't make it but I was exhausted I also worked 50+ hours a week at a physically demanding job. I had my next at 27. Less demanding job and the exhaustion want as bad. Unless my husband put the two youngest on his sleep schedule. Now I'm 42, my baby is 6 months old. I work part time but also am a treasurer for a non profit. My husband works nights. I seriously am so dead tired all the time. I will say I think a lot of it is my mental health. I've struggled with depression since my son was stillborn. And then my oldest was murdered in 2021. Both died in October 2005 and 2021. I'm so scared that my children will die that sometimes I can't sleep. I will say October has always been a complete crap shoot for me. My husband is hoping since baby was born in October it'll be better for me. But the exhaustion is just a lot