Mamas can you help

Ok- so I have heard about cluster feeds at 2mos and I'm thinking my LO has started this. She gets so antsy and hungry right after shes fed probably about 70% of her feeds. I talked to her peds and she said to keep it at what it is -- shes 8 wks (weds) 7pounds 4oz eating 3ozs of neosure with iron every 2/3 hrs depending on how fast she starts her hungry ques. She is a premie though which is what her peds was more concerned about because her digestive system is behind (which i started her on probiotics to help with her gas pains which has helped tremendously!)So I did try a 4oz feeding today for lunch because she just seemed starving for a whole hr after she had her 3ozs at her breakfast feeding but i noticed that she spit up twice and she usually never spits up..i dont wanna let my girl starve but also i dont want her belly to ache especially since i judt got her gas pains to stop a few wks back...is it too early to start with a little cereal, rice, or oatmeal in her bottle to help fill her up?