Nothing you mentioned sounds like a symptom of autism to me. My son has autism and I teach students with autism so I have alot of experience with it. ADD/ADHD does cause executive functioning deficits as well a processing issues which can cause some of the things you mentioned.

If she is doing well in school and these symptoms do not greatly impact her level of functioning then I would not stress over it. There are strategies she can use to help with these things as well. Such as a small hand held timer that can sit on her desk so she can self monitor her time for a task. Also, does she have a planner for school where she can be prompted to write things down she needs and will forget such as supplies and assignments? Making to do lists and items needed lists work well but she will most likely have to be reminded to do so. You can write down the directions home on an index card and have it laminated for her to keep handy when she forgets....cell phone is great for these things like lists and directions using a note taking app but I dont assume she has a phone.

The inattentiveness and forgetfulness is just part of the ADD though. The only help for that is meds, Although, I had a student who couldnt take meds because of a retinal disorder and the meds raised his blood pressure putting pressure on his retinas. His doctor prescribed a special vitamin regime to help and I know it included fish oil. It did help some.