Hi H.,
I don't know if any of this will help you, but this is what worked for us.
We used a snuggle nest so when the baby when down for a nap, I could lay next to her and touch her and once she was asleep, I left the room. Between 3 & 6 mos., I would put her in the curve of a boppy pillow on the floor while I did dishes, laundry etc. There were days she cried - and loudly, but being busy helped divert my attention so I didn't rucsh right in to rescue her. Eventually, she would fall asleep there. I would scoop her up and put her in her snuggle nest, but this way she was in a place where I could easily see her, so I knew she wasn't hurt when she cried. She and I both worked through the crying - and in hindsight, I can say it was probably harder on me. Then, at 6 months, when I put her to bed one night, I had put the snuggle nest in her crib earlier in the day. she fell asleep in my arms, I laid her in the snuggle nest in the crib -she slept all night, and within a week, the snuggle nest was removed.
Good luck!