My 18 month old isn't walking. she can cruise furniture, go for sitting to standing, walk between two people but won't let go on her on. walks/ runs on knees. is in physio and they don't see a physical reason. could this mean she has autism?

I understand your concerns. I will take the easy possibility first. I have seen us where a child does not feel comfortable walking because of the structure of his feet or legs or both. Sometimes putting the child in a three-quarter rigid soul , high top shoe. This will provide stability to the feet.There are many other reasons why your child is not walking. Please seek medical attention

I worry less about autism than I do a broader developmental neuromuscular disorder. I would schedule a visit with a developmental pediatrician or pediatric neurologist.

All the milestones should be assessed and a complete visit with your PCP is suggested. Assess her neurologic examination and muscle strength. If she has all other milestones met, then a more isolated problem may be present. Review her growth and development with your Pediatrician.