My daughter is 20 months old and we are still trying to find a good nap time for her. Right now her nap is anywhere from 11:45 to 12:30 depending on when she wakes up in the morning. She usually sleeps for an hour and a half but still seems so tired and has a hard time making it to bedtime. She will usually wake up crying and that's not normal for her. Before switching to one nap she was a great sleeper

Any idea of what I can do to help her sleep longer.

This is what we are doing now:

Dark room

Falls asleep on her own

Sound machine

5 hour 10 minute wake window

Lunch before so she is nice and full

Lots of play before her nap (typically park or swimming.)

Thanks again for any help.