Something else to think of is the possibility of spay incontinence. Is she spayed? if so at what age? Since this seems to be happening at times when she should be sleeping... that is typical of spay incontinence. Also YES the UTI would have a lot to do with the bad potty habits. The urgency that hits you when you have a UTI to go is soooo much worse than with out one. (Been there done that. UTi's are NO FUN right ladies

) After the UTI clears up You should have a much easier time training her. Mastiffs and danes are clean dogs (aside of the mountains of drool you'll have) and my male dane was potty trained by 14-16 weeks.
I also agree with Misty. If it is truly bad habits cleaning her sleeping area with white vinegar will eliminate the biologial element that draws dogs back to their potty areas. When training a behavior out you always have to clear all medical reasons first then you can safely assume it's behavioral.