hmm.
is she happy? healthy looking? are there any internal red flags going up? are her eyes glossy? her soft spot sunken at all? grey tone to her skin?
basically, if shes happy, healthy looking, no grey tone to her skin (unless of course she has that tone all the time), no red flags for you, glossy eyes, normal soft spot, etc, shes probably fine.
breastfed babies really bend the rules when it comes to growth. they are typically smaller. 1 lb smaller across the board. so dont worry unless, like i said, you have red flags. your instincts are important. so if you feel she is fine, dispite her growth, she is more than likely fine.
as far as those percentage charts, i HATE that doctors use them, but they dont explain to you really how they work.
basically, they are just comparing your kid to every other kid in her age group. its GROSSLY unfair because NO kid grows exactly the same as another. as long as she stays around in the same area of the graph, thats whats important, not where she compares to others. she doesnt need more calories, she doesnt need to eat more, she doesnt need extra formula - but its not a problem if you give it to her. formula has extra calories, so if you are doing it and its working for you, dont worry about it! :D
dont put the pressure on yourself. doctors "like to see" a lot of things that they dont because mom knows best. in EVERY SITUATION YOU KNOW BEST. shes your child. the doctor does NOT have the connection that you have with her. she never will. you are more important than the doctor! :D
just play it by ear. dont force solids if you dont want to, or if shes not ready.... but go for it if she is! dont worry about making sure she gets "more" as much as you worry that she is satisfied with whatever you do. making a baby eat when they are finished is only going to help her shut off her 'fullness' cues. not a good thing!
anyway, just follow your heart. you know. ;D doctors are wrong more often than we think!