My 3 year old daughter is scared to use the potty or toilet. We've tried toilet training a few times and she'll hold on all day to the point of screaming in pain. She is then completely distraught when she does finally 'let go'. She get's so upset that I let her put a nappy back on (I don't think it's worth a UTI at this stage?). She tells me when she's doing a wee or poo (in her nappy) and clearly has good bladder control but her fear of the potty/toilet is holding her back. I've tried so many different strategies, but she is so strong willed and just refuses to wear undies or sit on the potty/toilet.
Alternately, you could just stop buying the nappies altogether so as a default option they just aren’t in the house. This way you’re back in charge and she would have to follow your lead. Doing this will mean that she has to (at some stage) do a wee. Over a day or so this will teach her that really it’s OK and nothing to be frightened of. The behaviourists call this immersion training but really it depends on the parent’s tolerance and how willing they are to see it through. You’d need to make sure she’s drinking plenty of fluids so she does need to wee often, a UTI would be more likely if her urine is concentrated.
I’d think that all the other strategies you’re trying are probably just fine but she may be doing this to get attention? I’m not sure but at three with the signs you’re describing she’s old enough to train. This is a common issue too with kids who insist on having a nappy on to poo and ultimately, the only answer lies in parents not buying nappies so that they aren’t an option at all. Eventually the child has to use the toilet/potty and when they find out there’s nothing to fear then this reassures them and they just move on from needing nappies altogether.