do NOT "concentrate" her Formula! I can't believe your Pediatrician said to do that. If you do NOT add in the proper amount of water with the formula powder or add MORE powder than water... it will be TOO concentrated... and it will overload a baby's kidneys! Which is NOT good. The instructions on a Formula can is very specific... you need to follow that.
If anything, your Pediatrician can/should prescribe "polyvitamins" with iron, for your baby.
ALSO, at this age, a "baby" is NOT going to eat like an adult...at this age, they are merely getting used to "solids" and it will take time to eat like us.
Also, MANY kids/babies only "graze" and eat in bits. My son is like that AND he is a very PICKY eater. So what. No biggie. He is HEALTHY AND very well developed for his age... his "picky" eating has NOT affected him/his health/his development/his anything. AND he rarely gets sick, AND I give him vitamins.
I think, your baby is not ready to be eating in large amounts, nor eating like a 2 year old. She is only 9 months old... and at this age Breastmilk/Formula should be a baby's PRIMARY source of nutrition... NOT solids, and NOT other liquids. This, is according to my Pediatrician.
A "serving size" for a "baby"...is ONLY in terms of teaspoons, or tablespoons at the most.
She will eat more things in time. She is only 9 months old... their "taste buds" are not even fully developed and they don't "taste" like and adult... they go by texture too.
Bear in mind, that food phases will come and go ALL throughout childhood. Your baby is normal. Each baby/child....has food "preferences", JUST LIKE any adult.
Its okay.
If a baby is teething, the naturally, they will have a hard time eating... but its no biggie. They will not starve. Just make sure she remains hydrated.
All the best,
Susan