I'm sorry to hear you're struggling OP. I can't comment on adoption as I have no real knowledge of this, but I have been in a state of overwhelm with a baby under 1. While I had a DH, he was working away, I had no real family support, and I felt like a bit of a shit mum. Tired, and didn't feel the rush of love I had expected. Turns out it snuck up on me, once I got sleep and time to myself.
Do you get either at the moment? Would you consider your mental health team good, or do you need to look at changing supports or antidepressants? If you're on the wrong dose, it can make things worse I believe. Is paid childcare an option for relief, while you figure things out?
The very fact you're considering adoption from what it means for your child, rather than what it means for you, is indicative that you will do the right thing for them no matter what that is. ❤️ Maternal love is often a fierce, protective thing, instead of a soft, warm love I find.
Best of luck with your decision and your journey.