M.M.
Ok at 3 1/2 you are in the right window. Yes girls train faster than boys girls tend to at 2 and boys at 3, but you have not missed the "magic window". Sounds as if your daughter has other emotional developmental issues. Unless you refer her to a team (school districts offer this free of charge) to help you, you will have to tackle it now. Children are not considered developmentally behind with potty training until age 4. That is the reason Medical Assistance pays for diapers at age 4. So you do have a little amount of time. I do think your daughter's psycho/social development is playing a role in the delay and do recoomend you getting help with that, but potty training wise, I think you need to relax and stop speculating what is going to happen.
I personally would stop with the pull-ups. Just be done.... They even recommend this with children with HF Autism. Do not sit and try to negotiate with her. Just do not buy any more. I know this is a big move, especially at night and it may involve a lot of extra work on you, but if your goal is to get her out of diapers, it is just something you need to do. Do not sit and tell her the what ifs, plea with her or beg her. 3 year olds live in the here and now, not the what if predicted future. Yes, she held her urine for 8 hours; oh well you now know she has the physical muscle strength to do that as well as the psychological control. So now make her use those abilities everyday. Place her in regular clothes & panties. Skip the freakin potty at this point especially if she is pushing beyond a size XL pull-up. She is a bigger girl. Get the toliet insert and let her use the regular toliet. Prompt her to go to the bathroom every couple of hours. Now do not beg her, plea with her just nice little reminders. You give her options and choices when you ask her to go, when you plea with her or try negotiations.
Wake up tomorrow morning and do not say anything. Just put the panties on her and say "there you go." These are what you are wearing now. Every couple of hours tell her "Alley you need to go to the bathroom now." If she goes great, if not remind her in an hour. Make it an everyday exspectation and not something that is a choice.
Just think, what is the worst thing. You have more clothes to wash.... She gets a bladder infection which can be a pain, but does clear up. Even with that you have now accomplished a life skill...
BTW, I was one of those 4 yr old potty training parents. I was told to do it this way by a group of professionals and it worked in less than 24 hours. They told me it would work in less than 48 hrs... Since it went so well, I decided to try it with my younger child when she was 2 and it worked like a charm with her too. I felt bad at first but then realized I had so much anxiety about it, that my anxiety was also playing into the oldest anxiety. I thought it was a crazy idea when they told me, but it worked so well with the oldest, you see I did it again.... Good Luck....