Enid, far from being a crap mum, I'd 100% agree with what you are doing. What's the point in flogging yourselves?
With ds, when I changed his nappy, I'd say "when you're ready, you'll be able to do wee wees and poos in the potty or toilet", not every time, but I suppose quite often. He was interested in the topic of conversation, but would not sit on his potty at all, or the toilet. We didn't know any other kids who were training, but did know some who wore pants, so if we were with one of these kids I'd say -look andy wears pants, he doesn'y wear a nappy again - he's ready to use the potty or toilet and you will be soon too. And that was all I did. One day he asked to use the potty, which we always had out. I could have fallen over in shock. He was dry and 'clean' from that moment, and 2 days later dry at night too.
I really feel if they know what the score is, what to do & have the ability to pull their pants & trousers up & down, then you just need to guide and wait. He just goes off and does what he needs to do. In fact, I had to ask him to start telling me, as curious younger brother on more than one occasion found the wee wee first and tipped it all over the floor!
If she still isn't ready by the time the baby comes, it won't be a big deal - I had one and a half years of 2 in napppies! Maybe the arrival of the baby might be what she needs to decide she is ready - baby wears nappies, and I'm a big girl, and all that. When are you due? Good luck!