The incontinence, weight gain and energy level could certainly be due to low Thyroid. When you check the thyroid, be sure to have the full panel done, not just what normal blood work would show. It has to be sent out for the full panel, your vets normal workup will not include all the details you need to know.
It is not uncommon for older dogs to have incontence issues, however IMO, yours is a bit young for this to be happening, maybe if she were 12 to 14. It would still push for a UTI, many times they do not show up on the test… But if determined that really is incontinence, I have used the hormore replacement and it works great with no side effects.
I didn't know incontinence was one of the symptoms of hypothyroidism. So, I'm kind of glad to hear that. I know the weight gain and low energy level are definitely symptoms (I suffer from hypothyroidism myself). I will tell the vet to do the ful panel. Thanks for all the advice! This is such a great resource!