Living with Autism

i have a 2 year old daughter who seemed to be developing very well, until just after we had our second child 8 months ago. She babbled words better in the past, but at 2 has not developed clear words. she loves to listen to nursery rhymes and watch barney. she maintains eye contact when she is enjoying what you are saying or singing. she doesnt play with her younger sister, and generally does not play with her peers. She is very active, runs around the house a lot, loves to watch TV, and gets along well with us her parents. When adult visitors are around, she tries to drink from their glasses, but only pays attention to the children visitors when they try to take her toys. She responds from time to time when you call. she plays with us a lot; climbing, holding and snuggling around us. we are worried about her verbal and social skills with her peers. What should we do