Does the following sound like a realistic plan:
Last feed in room with low light on
Unlatch before she falls asleep
Into cot and sit with hands on chest/gentle stroking till she drops off
That sounds like a great start point to me.
The aim would be to completely seperate feeding and sleeping, so that the bedtime feed happens half an hour or so before sleep time and she goes from awake to asleep in the cot.
From the point you are now, how quickly you progress to that stage comes down to how urgent it is for you to get your baby sleeping independantly.
You may be absolutely unable/unwilling to comfort your baby at sleep time anymore, in which case you can go straight to leaving baby to cry. The other end of the scale is not wanting to give rise to any preventable distress in baby, so taking the longer term, slow, kind and gradual view but with the view towards independant sleep (as opposed to just cosleeping, which many may choose).
I'm of the more gentle route to independant sleep. But it's no quick fix so needs realistic expectations. I started from newborn with gentle gradual withdrawal, it took until 12 months to reach the point of 'put in cot standing, say night and leave' stage. But I've never ever tolerated any crying / shouting / grumbling / "singing" (or whatever word is used for a child vocsluding unhappiness) in the process at any time - hence it took a longer time than controlled crying at 5 months would have done.
If the above sounds reasonable, what would you do for night wakings? These are only occasional but she often doesn't wake fully and five minutes on the boob sends her off.
I'm not really sure where on the scale you lie in terms of how harsh you want to be, so it's hard to advise. You strike me as much more of a gentle parent, who's only stopped feeding to sleep because it's stopped working, rather than because you dictate you want it to stop (?)
In which case, if feeding in the night works - do it. There's no need on not to, comforting your child is not harmful to independant sleep.
Progress towards independant sleep at bedtime and naptime - so unlatching sooner and doing gradually more of the settling in-cot rather than at the Brest. Then gradually less in-cot settling. At least then yoy will have alternate comforting methods in your arsenal.
Try alternate comforting in the night, sometimes it may work but if not, there's always the breast. In time he may either just wake less frequently anyway, or be more tolerant of in-cot settling.
I'm not sure if I'm reading you right in this though. There at faster methods to get there, less gentle and more crying. You don't have to take the gentle route if it's not your parenting style.