hello you
Alex transitioned very early (13mo firmly on one nap) and I couldn't chop and change from one to two with him, we had to just go for one and it took him a week or so to adjust comfortably. He has always been v low sleep needs.
Sophie sounds more like Ben- she has always been v high sleep needs and wasn't properly on one nap until about 17.5mo. Once she started having 1-nap days, I would do two 1-nap days, and then a 2-nap day to catch up, then two 1-nap days, then a 2-nap day, etc. I found she got used to the longer A times quicker by doing 1 nap two days in a row then catching up sleep on the 3rd day. Constant switching daily from 1 to 2 naps just got her body clock in a mess. After a couple weeks she could handle three 1-nap days, then a 2-nap day, etc and then after a couple weeks of that it was 1-nap all the way.
I would go for 1 nap again today if you think you're not going to have a horrible OT night. I used to stretch Sophie's morning out gently by taking her out in the pushchair for a nice long time- a good hour or more of her sitting while we went round the shops, or to the park to feed the ducks, anything to pass the time so she was awake but not physically active to help her stop getting OT, does that make sense? That definitely helped her get through this stage.
hth, have a good day
K xxxxxxxxx