Margot doesn't show her overtiredness by mood or behaviour--except during the night. Overtiredness, especially cumulative, guarantees us night wakings and if she's not napping, I'll have even a harder time getting her back on track, so that's why I'm trying to be proactive.
The good news is that she napped for 1.5 hours today, so whatever she's been getting lately I guess hasn't been enough. The funny thing is that we've had jackhammers going inside our house due to some drain problems, so the house was loud, stinky and shaking for the better part of the day! The nap secret--found!
I think I'll just aim for a minimum 12 hour night leep on those days she doesn't nap and hope that I don't lose my job for having to cut out to get her down early!
Thank you both for your help.