This problem seems to be more about her awake time? Try to keep her up as long as you can, and lay her down when she is sleepy. When she is developmentally ready to stay awake longer and sleep longer, she will. Some babies just do this later than others. My day care baby is the same way with short naps, although he could care less when/if he eats.
Your body is used to the 3 hrly feedings, so it knows how much milk to make for that. She is used to the calories of 6 meals to help her sleep through, so if you knock it down to five feeds without uping her solids - she may wake up like you say. Makes sense.
As she naturally starts taking more solids you will be able to drop feeds, and she will be able to go longer between nursings. Babies usually change a lot at this age, 9-10 months, I'm hoping yours gives you a little relief soon! :wink: