Sorry, but I don't have much advice for you! Myles has never really had a consistent wake time from the get go. He is 22 months today, and I have found that the last few months there have just been so many things going on with him, like molars, eyeteeth, separation anxiety, talking, illnesses, reaching new milestones, etc.. I have really learned to relax and just go with the flow more, and trust me it took a long time to get there! I continue to maintain some structure, ensure that he continues to fall asleep independently, meet all his needs, and hope for the best. I've said it before and I'll say it again, they are little human beings, and no matter how many books we read or how much advice we take, sometimes there just is no magic solution, and they are not robots that we can program. They will have bad days and good days just like anyone.
Hang in there, we are all in the same boat!!!