Sleep training

My dd is almost 14 months and she cannot/won’t sleep alone. She was a premie and spent time in the nicu but when we brought her home she slept in her own bed till she got sick and I held her so she could sleep and breathe. Wellllll here we are now and she doesn’t sleep alone. If I try to put her down she get right up crying and carrying on and no nap happens. I tried cio (which wounded my soul) but it never took and she was miserable 😩. So now I hold her while she naps and yes she sleeps in bed with me (I really don’t want to hear opinions about sleeping with her). It was ok before cause it was easy for breastfeeding, but now I want my bed back lol. Any tips or ideas to make it less traumatic for everyone?