Ok, I think he's actually OT. Teeth are also notorious for causing EWs and sometimes shorter naps as well, so they are likely playing a part. I do still think he's ready for a bit of a push in A times, getting to 2.25-2.5 hr first thing in the morning and then another 2.5 hr after that.
As for the last two days, because of the short naps in the afternoon, his bedtime should have been brought forward a bit. That long A to bed is likely causing OT and thus the frequent NWs (along with teeth) and the EWs. Two days ago, after the 10 min nap in the car, I would have done BT at 6 pm, and yesterday, I wouldn't have gone later than 6:30 pm. 2.5 hr A after a 45 min nap is still pushing it a bit for a 5.5 mo old, and the day was really long since it started at 6 (after an hour awake not too much earlier). I know it's a bit daunting to put a LO to bed that early, but it usually doesn't make them wake earlier. Most babies will actually sleep better and longer on an earlier BT, because they are not OT.
If he did sleep 12hours at night how long should he sleep during the day? Should he still be on 3 naps a day?
Yes, he should still be on 3 naps a day. Once his A times get closer to 3 hr, he'll start to drop that CN, for most babies between 6-7 mo. With three naps, if they are full (meaning 2x1.5-2 hr naps, plus a CN) he'll probably only need 11-11.5 hr night sleep. When he drops the CN, that will likely move back closer to 12 hr. Ideal daytime sleep at this age is 3-4 hr with nights being 11-12 hr.
HTH!
