Okay - are you using the same litter as she had at the breeders? If not, then it may be an idea to get some the same - she may not like the litter you currently have so I would try a totally different litter in the second tray i.e. if you use non-clumping try clumping and so on. I know you have been praising her for going in the tray but try giving her a treat too.
Are both your trays open or covered. Have one of each if you can and make sure they are in a quiet place.

Do you have any other pets? I wonder if she is lonely - missing her siblings if she is so clingy and wanting attention and she is guaranteed to get it by weeing in the wrong places!

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Kaz

For kittens, joy is for the asking and smiles are for the giving