Does your daughter cry a lot? Does she spit up a lot? The things you described sound similar to my (now 11 yr old) son. He is not austistic but at 6 months of age when he was not getting better, he was finnaly hospitalized and tests were done. They discovered that he had a very bad case of REFLUX. After this was treated he began to be less fussy, wanted to be held, and even began smiling: )
As far as what I remember from my 7 year old son who IS autistic......When he was a baby he appeared perfectly normal and developing rather well. It was not until he was about 18 months of age that we noticed things. The thing that we noticed the most was his language. He talked and babbled normally but after one years of age, he said nothing, only grunts and moans. He began ralking again at age 3.
Good Luck