Anyone with LOs who wee "on demand", but who hate the feel of the potty / seat?

[sheeplikessleep]

My 22mth old wees when we are changing his nappy, on his mat and we say "do you want to wee wee?". He looks mightily pleased with himself after weeing and we give him attention/hug. It feels a bit like we are 'nappy training' lol! He understands the request and can wee when he wants.

Anyway, every time we attempt to put him near potty or toilet seat (the cushioned ones), he goes mad, desperately trying to get off. He hates the feel of it against his skin.

He's the same with walking on grass/sand, sitting in bath without bathmat, going into swimming pools where water is a bit cooler etc etc, we've only just managed to get him wearing sandles without socks. So, he is quite sensitive to 'touch'.

I know he is a bit early to potty train, but I'm pregnant, so if there is a chance we can get him started before his world is turned upside down with the new arrival, it would be good. His weeing when asked on the changing mat has made me think maybe he might be ready in some ways?

Any experiences appreciated.
Thanks