Hey I hope you don't mind if I chime in here.
I feel like I could have written your post myself - trouble is my LO is not quite a year old!

So it feels to me like we are heading towards where you currently are now, so I'd be interested in what anyone has to say.
I'm not sure what the recommended amounts of sleep are for a 15mo, but do you add up the total sleep your LO is getting over a 24hr period? It seems like your routine starts 'late' (as if 8am is late - Ha!) and ends early so your LO is doing less than a 12hr day with naps!
I guess it all comes down to how your LO is feeling, if they're grumpy and OT or not. My LO was still singing away after 5hrs A, resisting his nap today at 1:30pm after waking at 7:30am!!!
I hear you on the non-existant tired signs too, i just dont see anything anymore untill it's too late or he really is exhausted. The only thing I get is rubbing eyes occasionally and then sometimes before bed after a long day he "flops" his head round.
