Is she getting more active? Could u maybe start by stretching her out til like 9.30 instead of 9 (slowly slowly) But if she is generally tired i was going to suggest most of the above next. I used the sling and it was great. Now DD is too heavy for me to use while vacuuming.

I found that when DD gets worked up being hot makes her less likly to fall asleep so if she has been upset and is hot i put her to bed with the fan on low so she is cooled down to sleep. (i turn it off once she is sleeping