Oh ok. That's amazing that she's dry at night. Well done, Little Catkind! DD's nappies are full to bursting every morning.
I'm reading a website at the moment (Topffit, if anyone speaks German) about being nappy-free, and they talk about the difference between conventional potty training and EC being the difference between consciously having to hold wee in, and consciously having to relax the bladder muscles in order to wee. So, when potty training at age three, for example, children are told they have to hold everything in until they can get to a potty/loo. Whereas nappy-free babies learn from a very early age when to let everything out.
The example given is Mum saying to little one before a car journey, "Now, do you need the loo before we go?" The child says they don't need to go. Ten minutes later, Mum has to stop the car because they suddenly now do. An EC-ed child would have been able to go to the loo before they set off, because they are used to relaxing the bladder muscles and have never been forced to tense up and hold things in.
All this is my convoluted way of saying, Catkind, that perhaps EC isn't responsible for UTIs but rather may help avoid them! (Disclaimer: not a scientist, no idea about this in practice, just a mum with a baby that likes to poo on a potty.)