Hi, so sorry I haven't made it back to this for ages. Things were really busy here last week and on the weekend (birthday celebrations).
How have the last few days been? Have you had any more luck getting him to take a nap?
It sounds like he's had a lot of changes recently with the new house and starting PTing, and also teething.
If he's still OT and not napping, I'd be tempted maybe for a couple of days to try APOPing a nap. Eg you mentioned that he nodded off in the car. What about heading out for a drive (could be just a drive or could be on the way to somewhere you're heading for the afternoon), or a walk in the buggy, and let him nod off that way? Then you could wait until he wakes. As well as helping him catch up, it would also be a break for you from all these nap struggles as I know they can really wear you down. (BTDT with my DD1). WDYT?
Another option (which might or might not work) would be to try a sofa nap - e.g. snuggling with you with a bit of TV and see if he'll nod off - perhaps later in the afternoon. Just so he has enough to get through til BT. Or setting him up a cosy den with cushions, blankets etc?
Sometimes ppl find they have to be a bit more creative with naps at this age.
Also, have you read this? I don't think your LO sounds like he's ready to drop the nap completely yet, but there are lots of ideas about managing the transition, esp when naps get tricky.
The 1-0 transition...Advice and Tips to help you through.