Deb, if it makes you feel any better, V has been on one nap for a good couple of months, and she still is pretty tired by 11am, even though nap time is at noon. Of course, I am not home with her M-F because she's at the sitters for the nap, but over the past few weekends I've observed (and actually tried to pay attention) what's going on with her naps, esp. since she's been sleeping through the night consistently the past few weeks again. One Saturday I put her down at 11, because she was about to fall asleep during lunch, so I put her down. She only took 1.5hr nap (her standard is almost exactly 2hrs) and she was awake at 12:30 for the rest of the day which was entirely too early, but she won't catnap anymore. So I really have to make sure she doesn't go down till noon, no matter what her cues are, because otherwise, she won't take a good nap.
Now, this past Sunday I learned something else. She only needs to take a 2hr nap. She'd woken up early that morning (like 5:30), and I just shoved a sippy of milk in her face and went back to bed. She got up a bit late that morning - and I assumed it was because she'd had her sippy and then went back to sleep, because when I got her, the sippy was empty. So she took her nap at noon, and ended up sleeping for 3 hours!! I didn't wake her because I was taking a nap myself, and I thought she probably needed the extra sleep because of the early morning shenanigans that went on. WRONG. She did fine going to sleep that night, but was up talking and fussing between 2-3am. All because she had gotten too much sleep the day before. Since then she's had her 2hr naps, and things have been fine. So I'll know better next time, and not let her take the 3hr nap.
So all that to say, it is such trial and error. And her sleepy cues might not be 100% reliable, although I think the road you are on is a really good plan, and I wouldn't change a thing. Good luck with pushing the am nap!!