. How much time should a 4.5 months old should be awake between naps?
Just close to 2 hours.
Can or should you extend the awake time, how?
There's an announcement called "Wake to Sleep" which has information about extending naps.
Why is it that if you hold baby in your arms can sleep more than 45 min. as long as you hold her?
When you are holding your baby, you are acting as a sleep prop by soothing her to sleep into the next sleep cycle. When she is sleeping on her own, in her crib, she has to use her own skills-- which are still emerging. Falling asleep and staying asleep are skills.
She automatically dropped her df. She is growing ok. Should I worry?
It depends on her night sleep. If she seems to be fine at night, sleeping through, then don't worry about it. If she starts waking for food at night, then re-establish the dreamfeed.
Hope this helps!