Sorry you are struggling... I was so worried about this also. My difficult child 5.5 breast fed until 17mos, the only reason she stopped was because I had to leave town for a few days. She had never had a bottle before that, would not take one!!! So she latched onto that bottle after that... which made me feel horrible. I should have just given her the sippy cup... but who knew how bad she was?
She never had a blankie or a pacifier or a stuffed animal. So she was getting close to 4 and she still hadn't potty trained either and we didn't yet realize what was up with her, so we were of course thinking she would always have the bottle and diapers!!!
Now I realize it was her severe Sensory Integration Disorder (SID) for both of the issues. As well as some of the BiPolar (BP).
But she has some real oral issues toungue thrust, drooling, bitting nails, chewing hair. So of course I look back now and see the bottle as one more vice. We only gave it to her with milk upon waking, before nap and before bedtime, but she had to have it!!!
We stopped the am one first, changed to a sippy cup...she fought it a bit. We cheered her on... she regressed at times. We tried to never get mad at her. Then the nap one went away.... finally the pm one also. It wasn't easy it took a couple of weeks, and I think this was the time she adopted her stuffed puppy...
We tried giving them away to babies etc. she was having none of it. Basically when she was ready she was ready. As with potty training for her, at 4 yo she was ready.
I know you are dealing with different disorders than me and a boy, but maybe something will help!!!
Our 2.5 yo we just one day took the bottle away and showed up in the am with a sippy cup and said here... I was so stressed about it with the older one that I just went for it with difficult child 2 she was fine... but she also sucks her thumb and has to have her towelly... Occupational Therapist (OT) believes she has Sensory Integration Disorder (SID) but opposite of difficult child 1 (understimulated)
Anyway good luck... go with your gut you know what is best!!!