You say high risk, however you said you had protected sex meaning it was NO risk for HIV. You're getting a check up which is great for whatever you may have going on. HIV is not a worry for you. Protected sex equals no risk.
Benign prostate enlargement is common in older men, yes it does lead to more frequent urination but has nothing to do with there being a cancerous condition (prostates just get larger with age and can start being a nuisance when they press on nerves).
True enough, that is rare in young men. Your doctor will know more about you than we do (we did not even know your age).
There are many possible causes for frequent urination. eg. Do you drink a fair amount of caffeine (coffee, tea or soda pop)?
A urinary tract infection (UTI) would certainly do it. A bruised uretha could do it.
Anxiety is also a cause of frequent urination. I have that problem too.
How are those even related?
Anxiety can speed up your metabolism which can make you urinate more often. Anxiety also causes tension throughout the body including your bladder. The stress response (fight or flight) can cause you to remove waste more frequently.