I think your dentist was right to refer you for a diabetes check. You could have diabetes and/or another condition. Your doctor should consider other possible conditions at the same time.
I've had a lot of UTIs, which can be associated with undiagnosed diabetes. Whether you have diabetes or not, ask your doctor for advice about preventing and managing UTIs. No one should have to put up with them. One thing that made a difference for me was passing urine after 'being intimate', ie within 5-10 minutes, even when going to the loo is the last thing on your mind. This can flush out any bacteria that may have found their way inside. Also, use a lubricant (plain/hypo-allergenic), especially if you have dryness down there, as dryness can contribute to getting a UTI. If you do have diabetes, then treating it will often reduce the UTIs problem.