First of all Congrats on the toilet training

Is it possible to take a potty with you and just go to the car? gross I know but it might work.. Or use the child sized toilets. ( not everywhere has them though) Does she see you go to the shopping centre toilets? She might feel more comfortable if she see's you are fine..

Good Luck I hope you can solve the issue soon

my 21 month old son is fascinated with the toilet but he only sits on it. no wee's yet but I figure its a start..