Could my 8 month old be showing signs of Autism or other disorder?

My daughter just turned 8 months old- since day 1 we have had feeding issues, where she never wanted to drink her bottles, but loves baby food. I began to worry at 5 months old when she started holding her arms like she is about to fly ALL the time, and flaps them around every couple minutes. Her new thing, is she began to randomly shake her head. She does this only a few times a day, mostly while playing or eating her food. Her doctor is not concerned because she is meeting all other milestones, but I just can't stop thinking about it. She smiles, laughs and makes eye contact (when she wants too). She does not like to snuggle, but I think that could be just her...any advise??