hi! I feel your pain -- I had a very similar issue with my little boy. I needed to adjust his schedule. I didn't think he was ready for a 4 hour schedule because he was only 3 months...but he needed a change -- we did a 3.5 hour schedule which changed things to 3 naps during the day (in place of 3 plus the cat nap on a 3 hour schedule). His last feed was at 5:30 - bed at 7-7:30, and a dream feed at 10:00 or 10:30. what was happening with us, was he was not taking a full meal at the dreamfeed, and was waking up several times a night.
the 3.5 was a bit of a stretch for him to stay awake...but he gradually was able to, then move to a 4 hour schedule.
Good luck!