Oy ladies, I wish I could hug each and every one of you. I know what it's like. We've been doing it for over a year now :-) There is something so different between being up at 5/5:30 to say being up at even 6 or 6:30. It seems to make all the difference to me anyway.
I don't want to contradict the lovely Anna because she is a veteran and my hero and basically gives me hope for Finn but I do want to let you know what has worked for us...finally. We're not in a perfect place but certainly have had more luck than before.
We know on some level that we are only getting between 10-10.5 hours. That's all he'll give us and really, looking back, that's all he has done. We used to be a huge fan of earlier bedtimes, but at some stage during all this it has meant a much earlier wake-up, at times it became 4:45/5 or even earlier - we have learned that he does not tack sleep on to his nights no matter how hard we try. We would be pulling our hair out because he was so tired in the morning but we had to go to one nap at 12 mths for daycare and really he is not one to go for a different routine on the weekends, so it meant he was pretty cranky until his nap. Then he would do a great nap, for that we have been blessed. But always always those 10 hour nights, sometimes even less.
At around 10 mths I think it was, we discovered that if we gave him a bottle at his EW he would go back to sleep. It meant he was still tired enough, it also meant that for some reason he didn't have the capacity to do it on his own, for whatever reason, he was given every self-soothing tool in the book but yet he could not roll over and go back to sleep for that last hour or so. So we did the bottle out of desperation. I quickly decided that was not the best route, in light of the fact that 1) he has most of his teeth (2 yr molars pending) and 2) it may turn habitual and in fact cause the EW at some point. So after a big LONG post on here, we ditched the bottle and went for a later bedtime. Yes that's right, a LATER bedtime. We decided not to cut his nap because again, no tacking sleep on, so we let him nap as long as he wants (most days at home is 2 - 2.5 hrs) and then a later bedtime.
The theory for us is that he needs to be SO tired at that EW that he will go back to sleep. He was too rested after early bedtime to do it, so the later bedtime set him up for a forced short night and he would have to learn to go back to sleep.
And he did, over time, with some derailment for illness etc. We now get 10.5-11 hour nights - he sleeps 7:30 - 6 or even dare I say, after 6 most nights now. Today was 6:30! I know some of you are thinking, but 6 is still early but as I said, it can make all the difference to your day than a kid who gets up at 5 or 5:30. The other thing is that he grew into A times which would work best with his sleep needs. Before that he was just sleeping less but not able to handle the times that he needed to be awake.
Anna has covered most of the tried and true tips up there, basically do not reinforce that EW. It's not time to start the day, leave LO in the dark and work on how to fix the issue rather than accepting that as a new wake up time. I went through stages of accepting it and coming back here to vent and post about it, and eventually whether it was just time and development, or my attitude towards it, we have made some progress here.
If your LO has done longer nights and has just been derailed, I think you can probably rest assured that you will get back there. It's just a phase, a stage, something is going on in their world and they need a slight reboot. You should be able to tweak and get yourself back on track.
If your LO is low sleep needs or just not developmentally ready to do longer nights, then you have to pick a routine that will work best for your family while maximizing sleep for your LO.