she is WAY WAY WAY too young to go to only one nap. PLEASE keep her at 2 naps for at least another 4 to 8 months. I found in my years as a daycare provider that the majority of toddler tantrums and terrible twos are due to lack of sleep. You can make her morning nap less, waking her after an hour to an hour in a half, but don't eliminate them please.
Now about the eating, it sounds like she is RIGHT on track!! At that age their bodies need less energy as the growth slows down tremendously. So, it's ok for her to eat less. Also they should be on table food completely by 12 mos old, so she is telling you that she is right on schedule for that. Almost every single adult food can be chopped in small enough pieces or steamed to a mushy enough texture that she can eat it. Don't give her large portions either, they only have a stomach as big as their fist. A TABLESPOON of each food group is more then enough for a meal for her.
There is a great book that you might want to get, by William G Wilkoff, MD called Coping with a Picky Eater that every parent or provider of kids should read and have a copy of. http://www.amazon.com/Coping-Picky-Eater-Perplexed-Parent...