
Can I politely suggest that comparing a toy breed to a Spaniel is not sensible. In my experience, having kept several toy breeds as well as Collies, the little ones do take far longer. My Border Collie got it right while just a pup, yet I've known toy breeds that have been well past 8 months to get clean.
It's nothing to do with being 'thick.' The 3 most intelligent breeds according to the experts are
1. Border Collie
2. Poodle
3. GSD
And I've trained a Toy Poodle in obedience and tracking, but she still took an age to toilet train. While I appreciate what you are saying about the 8 - 12 week period, it's a known fact that toy breeds are often kept until they're 12 weeks before homing, as a matter of course. Certainly a lot of the toy breed clubs recommend this.
I would go back to basics just as you would with any new older dog, and treat as an 8 week old, taking outside every hour - and, importantly, staying with pup so that praise can be lavish when you get the desired wee/poo. If you do this you will get there in the end. Don't despair, just remember she's not a Spaniel! :-)