Sorry to hear that you are having sleep hassles
How long has it been going on for? Emily also went through a phase about 2 months ago where she would fight her sleep at night. But, I then changed her night routine and became a bit more "strict" with her. She soon figured out that I meant business and now she goes down beautifully at night. I must also add that Em's bedtime has gotten later as well and I am not too phased about that. I let her play until she begins to nag before I take her upstairs for a bath and then bedtime. So most nights she goes to sleep at about 20:30 now. I'd rather have a later, easier bedtime than a hassle. I definitely don't let her go past 9, but I don't force her to go to sleep if I can tell that she still wants to play at 8:00.
Could be the holidays? were you away or out late at night with her? Could be that it messed with her routine.
The only thing I can suggest is that you create a routine and stick to it no matter what. THat unfortunately means no driving to sleep, etc.
Our routine:
Bath
Then I sit with her on her rocking chair while she drinks her bottle.
Cuddle and rock for 2-5 minutes after bottle is done
Then I put her in her bed and say night
I usually stay in her room for another 2-5 minutes and then I walk out.
Some nights she calls me back and I sit with her for an extra few minutes, but most nights she turns around and goes to sleep when I walk out.
I think its definitely developmental and I can see Emily trying to push the boundaries with alot of things at this age to see how much I will tolerate, so I think its important to just "stick to your guns" with this.
Good luck - I know how tiring it can be