Well DS1 started daycare last yr in may (age 2.5) as i thought he might benefit from some social interaction with other kids. (i'm a SAHM and he refused to even acknowledge the existance of his 6 mth old baby brother) He was practicly non verbal (would babble), food and sensory issues, co-ordination issues and is also very independent little boy and wasn't interested in interacting with anyone except DH and I and, like you little boy, would walk around aimlessly going from one toy/object to the next at home and daycare.
Now, almost 10 months on, he LOVES going to daycare and looks forward to it and shows me by dragging around and throwing his daycare bag at me in the days leading up to daycare day His speech has improved a lot and can say a few communicative words, interacts with other children and by that i mean he will laugh at other kids if they do something he thinks is funny (something simple as other kids running past him or making a funny noise) but he is still very independant and i think always will be. His co-ordination has improved a bit and i think most importantly, when he has had a developmental 'growth spurt' he dosn't regress as much as he used to.
Please don't be hard on yourself, you sond like such a fantastic mum and you only want the best for your DS. He will find his way i'm sure but everything takes time in our autistic world