M was a little older when we went through this (but she is very high sleep needs, and I know that Ava is much lower sleep needs), but when she started babbling before she went to sleep it was because of OT. She has never been able to babble for a while and then just fall asleep (I know a lot of them do) - she would always end up missing her sleep window and getting OT. One thing that I did discover, though, was that it was important to wake her by a certain time after her nap (for us it was 2.30) to make sure that her A to bed was long enough. Even if she had messed around before going to sleep for her nap, I found that the best way to keep her on track was to wake her despite the short nap, go for bed at the usual time and take the next day from there.
The way we got out of the rut was to wake her earlier in the morning (so 6.45 rather than 7/7.15) and offer her a slightly earlier nap (pulled back from 12.45 to 12.30, finishing at 2.30) and a slightly later bedtime (moved from 6.45 to 7/7.15). This got her back to falling asleep straight away, and then once we were back in the swing of things we were able to go back to waking her a bit later in the morning and not stress so much about exactly what time she started her nap
Not sure if any of this will help, but I hope it does.