If there is urinary infection,you cant hold for too long....in case of infection there is frequrncy and urgency in micturition.you may feel pain at the end of micturition.go for urinary culture and sensitivity test.
First of all
1. do you pain or discomfort when you pass urine?
2. Do you experience feverishness or chills?
If yes, then it could be a sign of urinary infection. Just increased urine frequency can also be a sign of urine infection, but it is unlikely without other symptoms.
At 21 years, generally your health is robust and it can fight infections well.
A good consultation by a Gynecologist will help understand your problem.
If you have had sexual relationship, and are now experiencing frequency. then it could be a sign of sexually transmitted disease too.
what ever the cause, a gynec examination, FOLLOWED by urine test will help clear out the picture.
As a young person i would like to mention that you must practice good vulval hygiene measures.
1. after a bath, or unination or motion passage when you wipe yourself, wipe from front to back and NOT from back to front. The anal area is inhabited by many organisms and if one wipes from back to front, it can spread the organisms in the urinary area. This can cause repeated infections
2. Before menses, trim your pubic hair short to prevent blood from getting entangled in hairs
3. use cotton underwear to prevent sweating, this prevents fungal infections too