Potty trouble - dry when naked but wee's in clothes? :-/

My daughter is 3 years 1 month old and was recently diagnosed as ASD. Her "issues" are mainly sensory (very noise-sensitive, can hear things we can't) some social and other issues as well. Prior to her diagnoses we started potty training. It took a while but she uses the potty at home - although refuses to contemplate a public / nursery / grandparent toilet (which is not so much of an issue yet given the fact she's terrified of toilets - she can hear the pipes). She is dry all day, but only when she is naked or pantless. She has been 'dry' for almost a month now, but as soon as she puts on big girl fabric pants, she wee's. We've tried pull-ups and she treats them like a nappy, although she asks for one to have a poo. She can go a few hours between wee's, but if we need to go out, we have to dress her - which means accidents. I've tried the padded fabric pants, cloth nappies, but it's like the feeling of anything covering her confuses her. Has anyone else experienced this and how did you overcome it? She goes to Nursery twice a week and they are keen to help, but are stuck for ideas Sealed