Yeah, we are averaging 11.5 h with or without a nap. It seems that if F naps for 1 h, the the night will be 10 h and if he doesn't nap night is around 11-11.5 h. It is what it is, I guess. I am a little stressed about it, as it doesn't seem enough for him now (a lot of bad behavior) but there's not much I can do, and possibly the bad behavior is developmental. I'm not so sure it will lengthen though, I think that it may be his average needs. I know there will likely be periods of higher sleep needs and periods of lower sleep needs, as there have always been.
We are also having lots of nnd, we offer nap every day putting a timer and he sometimes sleeps sometimes not (at preschool he naps though mostly), but it seems if he falls asleep it is always after 2.45 pm, so very late...
So, we are in a similar boat, I think!