I’m 15 and I can’t cum? Why?

Patient: Hi I’m a 15 y male and I’ve never cummed. I know that I have precummed before but never acutally had ejaculated. I have a 4inch penis erect and don’t think I fully went thru puberty because my voice is still higher and I’ve had hair down below for a year and am just getting armpit hair. Am I a late bloomer and is that why I can’t cum?

Symptoms: Can’t cum

Doctor: