I don’t see how that’s possible either. My LO definitely would not have been OT from that but she does have pretty low sleep needs. Maybe she’s UT at BT, have you tried more AT before BT? When we were in 2 naps she’d mostly have shorter naps, we’d have something like this:
WU 730
A 4:00
S 1130-1215
A 3:45
CN 4-430
A 3-3:30
BT 730/8
I know this looks like no day sleep at all but her naps only got longer since getting more AT and switching to one nap. Anything longer than 45m was pretty rare for us. She always has had a long AT in the morning, getting shorter as the day goes on. But if she had a long morning nap like that she would probably need more AT in the afternoon. I’d usually have to cap her CN so BT wasn’t too late.
I’ve had wake ups shortly after going to bed for both OT and UT. Is she upset and sleepy when she wakes up after BT or happy? I can usually tell pretty easily when she wakes up if she’s OT or UT.
Maybe the morning nap needs to be capped to 1.5h so you can still have 2 naps with a reasonable BT?