Totally not aiming this at you OP, but I honestly think some of the "not ready" thing is bonkers. Babies are born being able to signal to parents when they need to wee/poop, it's just in the West, on the whole, we ignore this and effectively teach them to soil themselves in nappies for years. (Humans didn't used to wear nappies, and in some cultures they still don't - googled elimination communication).
So 'potty training' is really just us helping them to relearn this forgotten skill, and it obviously takes time to unlearn what we've previously taught them. So yes, the older they get the quicker it can be to teach them (as it would any skill), but also by leaving them in nappies for so long it can just further ingrain the behaviour. Which is likely why we have so many four and five year olds at school in nappies.
It's confusing for them when they are suddenly expected to go on the potty when we have taught them to use a nappy, but just like any new thing that doesn't mean we should necessarily avoid it just because it currently feels unknown to them.
Are there ways you can help her to feel like being on the potty is an ok thing to do? I used to find that story books or a little box of raisins did the trick to distract my LOs. And certain points of the day - when they first wake up in the morning or nap time, half an hour after a drink, etc.
My ds1 was 13 months when he would consistently tell us he needed the potty for poops, wees took a couple of months longer, my ds2 was more like 18 months, but it was really all about me not being ready (two kids and frazzled) rather than him. Not sharing that because I think that's spectacular, in fact it would have been the norm a couple of decades ago, but just to say that later isn't necessarily easier.
But be kind to yourself, and try to not let it stress you out. It's not a linear neat and tidy process, and that's normal!