Weird sleeping habits.

My daughter has been having weird sleeping habits since a few days before she turned 6 months. So about a week now. I think she is trying to shed a nap. She usually takes 3 naps a day then goes to bed around 7 and sleeps until 7......now if she has 3 naps she doesn't go to bed until 8:30-9 or she has 2 naps and goes to bed around 7 like normal.....it's kind of a flip flop thing but sometimes we do stuff so that changes it too I'm sure. Not sure how much sense this has made but does anyone else have this going on? Or has anyone else gone through this. Thanks!