Yuliya - that is awesome that she goes from the DF until the morning.
I would keep the morning nap longer. The quality REM sleep is similar to that of night sleep, but maybe try not extending any other nap. Your rule of thumb is if she is happy waking up from a nap, then let her.
I had something similar with the cranky/fussy thing after the bath. One of the things that I did that helped immensely was feed her before the bath, do the massage/bath/night ritual and then feed her after that about 10 minutes before the bath. It is definitely easier to teach your LO that the bath is part of the night ritual. now no matter what time I give my LO her bath, she wants to go to bed within about 20 minutes of her bath. So, if we leave the house early for a date or something, I don't give her a bath any more other wise she would go right to sleep! It is very handy!
If you give her more A time after the bath, that is fine, but keep it in the confines of your night ritual. So, if you read her stories, just read a few extra ones, so maybe instead of 1 book, it's 3. Or if you sing her songs, instead of one song, it's 4. I would avoid letting her get on the floor and playing with her toys other wise you may work her up again.
If her good days were appx 15 -15.5 hrs a day, that is what you want to continue to shoot for in the routine. If she starts getting 6-7 hrs of day time sleep, it's going to come out of the night sleep, if you're putting her down at 6 and she sleeps until 7, then that is going to come out of the day time sleep. Make sense? If she's getting an earlier bed time and nap extensions, something is going to give, and it sounds like the night time sleep.
The PU/PD is a sleep tool. There is some great info on it on the PU/PD boards. For our LO though, it was too stimulating until she was about 5 mos, so we continued our version of sh/pt. (she didn't like the pt part so we did a sh/rub) At 5 mos though, PU/PD worked really well. Just pay attention to how she takes to it.
HTH