I did a course on this not long ago, as a follow on from maternity nurse training. It was very much focused on 'attachment parenting'. The solution offered was to get into the cot with your little one! How practical this would be in reality I don't know. The idea is that you make the transition from nursing to sleep to putting down awake and them settling themselves in lots of little steps rather than one big jolting change.
So initially your new routine would be:
Breastfeed her in the same place you usually do, but only until sleepy, not asleep.
Lay her in the cot and get in with her.
She may well get upset because it's not what she's used to, but she has the reassurance of having you there as comfort.
Lie with her until she falls asleep. It may take a long time. Don't let her nurse after the initial feed before bed - you're trying to disassociate between your breasts and the ability to fall asleep. But Shhh, stroke, pat, sing, whatever works for you. BUT bear in mind any other sleep props you introduce now she will expect going forward. Does she have a special teddy? If not now would be a good time to get one. You can keep it in your bra/down your top for a couple of hours before bed, then it's hers. ONLY for bedtime, not to be played with during the day.
Continue with this every night. If she wakes you can get in with her, but not feed. This is the first step in the transition.
When she settles well like this (and make no mistake, it could take weeks!) try lounging in a beanbag next to the cot instead of getting in with her. You can stroke her hand or pat through the bars if your arm fits. Continue this for the next few weeks, or however long it takes for her to settle well.
When she's consistently settling with you next to her, move the beanbag nearer the door so you're in the room but not next to her/patting any move. You can still Shhh or sing or whatever but you're too far away to touch.
When she's used to this sit in the doorway.
When she's used to this stop sitting with her at all.
It could take months to crack it this way (or it could take a few days, every child is different and so is their ability to adapt to new 'rules'!
You could look into controlled crying (NOT cry it out!). The introduction of a teddy you've been 'wearing' and maybe a soothing sounds app or something will help you feel like you're not abandoning her, and doing what you can to keep things positive. She's likely to 'get it' much faster with Controlled Crying, and be consistently falling asleep alone within a couple of weeks, but there is the fear of deeper longer term effects.
You could just continue as you are, feeding to sleep, even go full 'attachment parent' and co sleep until she's ready to stop (could be another 8 years!!)
It is a tough one OP. The thing is what works like an absolute charm for one might just be traumatizing for another, and there's no way to know until you try. But whatever you do, try to be calm and consistent. Good luck!