S.C.
My son had a similar problem. Always feeling like he had to go pee but didn't. We also ruled out UTI. Took him to a Urologist at Nemours. With ultrasound they found that he was really, really constipated. The doctor said when the bowel is full like that it presses on the bladder making it spasm and feel like he has to go pee. We never would have suspected constipation because he was pooping regularly just not enough. He prescribed the laxative Miralax (available over the counter). We started using it, he started pooping and the problem went away. Might be worth a try.