My DD is 21 months old and displays none of the red flags for autism, she is a very good communicator, is speaking in sentences (the one I remember from today was 'breadsticks over there on table' but she is doing it quite a lot). She has good eye contact, responds to her name etc but I have noticed recently she does often walk on tiptoes. Could this be a warning sign despite everything else? Thanks in advance, anxious single mum.