Thank you for giving us ALL the information we usually have to ask for. My boys were also preemie's and difficult child 1 had some minor issues so I also chalked a lot of the developmental stuff up to being a preemie. He was only a month or two behind his twin brother, who was right on track.
I think there is more going on that ADHD. That is just my opinion. If the adderall works for the inattentiveness, that might be part of the picture. Have you checked into a neuropsychologist? I would start there. I would also have a thorough Occupational Therapist (OT) evaluation done. If she had sensory issues before, she probably still has them. The picky eating could be medication but it could also be more intense sensory stuff. difficult child 1 has always been a picky eater. As he got older, patterns began to emerge. Now, he will eat the same things for weeks then suddenly change his "food obsession". My philosophy since he's so small for his age is that as long as he eats, I don't care what he eats. I don't keep junk food in our house so I guess that's never been a problem.
So there, now you have my two cents. neuropsychologist and Occupational Therapist (OT) evaluations to start with.