What length nights does he give you if he goes down early? Just wondering if you will get a decent WU if you do a 6pm bedtime tonight? That seems reasonable to me given the early start and from a 1pm wake up, but I know not all LOs do well with early nights. They really helped here though when we first went to 1nap, lots of 11-1ish naps and 6pm BT, and she would usually sleep until at least 6:30 the next morning.
(((Hugs))), it seems like it's so easy to get into OT with this transition. At least with 3-2 if one nap goes bad there's at least one more to make up for it, but once you're on one nap it's one shot in the day to get some decent sleep and that's it! I found it got a lot easier once dd could consistently make it to 12:30 for the nap. Before then we got lots of OT and naps under 2hrs, but once she could go down after lunch and could really handle the A time we had a great routine for months and it's only starting to change now at almost 2.
Also, you never know with teeth. Don't despair! My dd's first 8 teeth were horrendous so I was dreading the molars and canines, yk the supposedly 'bad' ones. She ended up cutting all of those 8 at the same time and she was fine. Not one single tooth related issue, and we had the whole works before. Weird!