Hi lesorl
Sorry your still going through it with this horrible transition, I haven't been on the 2-1thread as much lately. I was going to say exactly what everyone else has, I would go for it now with the 1 nap. You've stuck it out until she is that little bit older, hopefully now she will do the switch and that will pretty much be the end of it, well thats to say after a couple of months maybe of her getting used to new routine.
Lily had SA of a sort when going through this transition and serious teething too. It doesn't make it any easier. I always gave her meds before sleep for teething, what type depended how badly I thought she was hurting that day and I did tons of APOP for the SA. My thoughts where that sleep was so much more important and although its no fun correcting the AP it is relatively easily done, especially when they are no longer so OT as the OT tends to make them more clingy at nap/bed times.
I used WI/PD/WO when lily was first on 1 nap to try to extend it, as she would generally only take 45mins-1hr. I also tried w2s a few times, think it helped but not 100% on that. I kept up trying to extend her nap for at least a month (may of been longer) before I got any results. Then it took another good month+ of doing wi/pd/wo at 45min mark to get longer nap and eventually she started to sleep right through the wake up and take a full 1.15-1.45hr nap.
I didn't bother doing 2naps once I committed to 1nap, even on really early wake up days. I just kept nap at 11am everyday and after about a week her 5am wake ups jumped up to 6am on there own, I believe purely because of the consistency of her day, it really helped.