Not taking meds my bladder fills up fast, even when i havent drank water. it fill up within the hour, for 6 hours a couple days ago. once i even had to pee 15 minutes after i had already gone. and i only took very small sips of water that morning?

You may have a small bladder capacity or overactive bladder rather than a need to pass large volumes of urine daily despite not drinking large amounts of fluids. I recommend measuring your daily fluid intake & your daily urine output. If you void much.more than you drink,you may have diabetes insipidus or trouble with your kidney concentrating urine. A urinalysis' specific gravity checks this

Avoid or reduce intake of soda, tea, coffee and alcohol. Try to hold it for 5-10 minutes longer when you get the urge by distracting yourself with something. If that does not help- it should- pl get a urine test and see a Urologist or your MD. I think you will improve gradually.