Hi, Casey. At this time of new developments with your lo's eating habits, I would recommend keeping a journal of her sleeps, feeds, and A times. That way, you will probably be able to see a pattern develop and be able to set your new "routine". Of course, nothing has to be set in stone, and each feed doesn't have to be exactly 4 hrs to the dot in between. Just as Noelle mentioned, you may have some different times during the day, and each day could be different for a little while.
When my dd napped past her regular feed time one day and I lost track of time myself, this was when we dropped a feed and shifted to a 4 hour schedule. It was very similar to your experience.
Best wishes!