Been having strange bladder problems,not sure if its related to

I'm 13 years old,and have been having problems,like if i drink not even that much i get a sudden strong urge to pee a hour later. The urge is so bad that i leak a bit and have to run to the bathroom.Sometimes if i try to ignore the urge it gets worse and i feel like i am about to wet myself.I have constipation problems too and the doctor always says its the poop pushing on the bladder,but im getting better from the constipation now. I never use the bathrooms at school,due to a anxiety issue,so when its time to go home,i have to walk fast to the bus and sit down right away because i feel like i am about to pee myself.But then other times i don't even feel like going and then i suddenly have to go extremely bad. I'm worried because i keep getting closer and closer to wetting myself in public or at home. I'm afraid to go to the doctor because she will just say the same thing and not help,same with my mom.
A staff member has to wait for you outside of the bathroom btw. plus theres only one stall so people are waiting out there in line. I also have trouble starting my pee flow,and once i go its very little.

If you need more details, i don't mind if you ask.

Thanks