Please do not just go on your previous symptoms of UTI. Get your urine routine and microscopy tests done. Sometimes you are with no or very mild symptoms when there is UTI.
Secondly check for sugars, get ultrasound
abdomen and pelvis done before you reach to conclusion of having serious condition like cancer.
Your thyroid is under control and weight gain can not be blamed always due to your hypothyroidism
. Watch your food intake and energy expenditure.
Once the reports are available your doctor will guide you further. Take care.