Can you more or less predict when she will need the toilet? I.e., first thing in the morning, before or after play, before or after eating?
I ask because we were desperate with our dog and, as sad as this sounds, we wrote down the times and situations every single time our dog toileted for a week, to get an idea of when she was likely to need to go. Then at those times we put her on a lead, got some roast chicken out of the fridge, and took her into the garden to a particular area in the garden, and walked her back and forth. No playing or fun or interaction - this was all about getting her to go to the toilet. If she did wee/poo, then we said 'Go wee' when she started to go, made a huge fuss when she finished, lots of praise, and fed her several pieces of chicken.
We also said 'Go wee' whenever she toileted out on walks and rewarded and praised her.
We tried to head off or predict any times she might go indoors, but of we missed it, whenever she had an accident indoors, we ignored her - no treats, no 'Go wee' cue words.
Our aim was to link the cue words, great reward (chicken) and praise with toileting outside, versus no reward and no praise inside.
Eventually, we could take her in the garden, say 'Go wee', and she would start sniffing around and then wee. When that happened, we still went outside with her, but off the lead and said the cue words so that she learnt the difference between going out for the toilet and going out for a play/explore. She now also pretty much always goes in the spot we took her to on the lead when we were training her.
It's the one thing that took AGES with our dog. She was great at all other training, but just didn't get toilet training for months. It was because we pad-trained indoors first, which we really regretted! She got it eventually though with a lot of persistence and chicken!
Oh and we have since trained her to ring bells to let us know when she wants to go out to the toilet. She loves training in general, so this added an element of fun and worked really well for her.