Have really bad urges to pee

I posted a question on this yesterday but I wanted to go in-depth with everything. I've been having, for like two months, the almost unbearable urge to pee. It started when I was at camp. I had never been there before and we went around this town doing projects and we learned info etc. The way we got around the town was by bus. I had no idea where we were going or how long it would take to get there in this town. One time on the bus I had to pee an I couldn't cause we were on the bus in practically the middle of nowhere. That's when it all started. Since then, and including the rest of camp, I have had to pee almost every hour and before I got in a car I would go cause I was/am petrified I will have that urge again and not be able to go. I went to the doctor, they took two blood test and a urine test and everything came back normal. The doctor said I don't have a urinary tract infection. So I have no idea what's wrong. Now back in school and I have to pee so much. In the morning, I take the bus, and I have to leave my house at 6:30. Before I leave, the time span of about 6:18-6:30 I pee 5 or 6 times and have 3-5 bowl movements (medium amount) I take a tums before that at like 6. I have the unbearable urge to pee waiting for he bus to arrive. It's horrible I feel like I'm gonna pee my pants. Then at school I pee before 1st 2nd and 4th period. I go pee after lunch and then I can last for 3 hours till it's time to leave. I pee 2-3 times before getting on the bus to go home. Mostly if I think about going to the bathroom I have to or if someone else goes I have to. And I just can't not think about it! What could it be??? How could I fix it and do you have any tips? Like taking your mind off of peeing or any tips!!!! This is ruining my life :( Thank you so much please reply. Ps: I'm a teenager (15).