Hello from spirited refluxer mom number 3 here
! Luke's reflux got way better with solids and by around 8 months it was pretty much gone and we stopped meds completely.
I agree with pp's that 7mo is pretty young for 1 nap and try to keep the 2 nap routine as long as possible if you can.
I just wanted to add two things. First, that at a certain point I think after 6 months or so, tired signs become harder to read and it's necessary to watch the clock ((almost)) as closely as you lo so you can keep naps balanced. And second, that 7-8 mo is a pretty common age to start a little nap strike. My ds did it as well for about a month. At that time for us it was nice weather so I started taking him out in the stroller for his second nap on most days just to be sure he would get it. It is a little AP but he could settle himself for regular sleep so it did no harm. I would do your best to get him to nap at regular times.
Is it possible you can try a much earlier am nap than you had been doing and see if he is able to get settled? Could it be that his morning A time is way too long and he's getting really OT?
Sending sleeping vibes your way, must be tough getting so little sleep while you're PG! x