I have mild chronic balanitis,antifungal cream didn't work,awaiting swab results. will i get gangrene and penis amputation? i'm seeing urologist soon

Unlikely: cannot say in your particular case, but generally, it isn't that serious a condition

No DM I presume: Just chr balanitis -that too mild won't cause gangrene and spontaneous amputation as you fear. Proper follow up with an urologist ,you are doing already. Find out the cause of balanitis. A second opinion from a dermatologist will help to r/o some other conditions which may be there like erosive lichen planus etc, which we may be treating as balanitis.

Of course not: Balanitis, phimosis, is due to fermentation by bacteria in tiny drops of urine under the foreskin. Shower daily, retracting the skin to rinse it off. Whenever passing urine, keep the skin back for a moment and blot off the urine from the area. Castellani solution (clear) is very effective. You will need to request it from the pharmacist. A circumcision is routine, quick and easy, always cures it.

No: Gangrene is when body tissue necrosis or dies whether due to lack of circulation or major infection that is left untreated. It is not likely that you will develop gangrene from a case of mild chonic balanitis which is mild inflammation of the glans penis. And definitely it should not cause amputation. Keep your upcoming appointment with your urologist but if you are really worried go to the ER.