Testosterone Replacement Therapy for Men

Testosterone replacement therapy is a prescription answer to a specific diagnosis. The sources draw that boundary clearly.
Who the prescription is for
The site my.clevelandclinic.org says testosterone replacement therapy (TRT) is an option for men who have low testosterone levels due to male hypogonadism. In official terms, testosterone products are approved by the FDA only for men who lack or have low testosterone in conjunction with an associated medical condition.
Whatever you were told in a clinic, that sentence is the benchmark. For the exact wording, the FDA keeps its own page, Testosterone Information.
What belongs with a clinician
Whether your levels are low, and why, is a clinical question. It is not one to settle from a symptom list or a clinic brochure. Healthline offers a readable overview of hormone replacement therapy for men that works as preparation for that appointment.
Four articles on this decision
Read FDA Labeling on Testosterone Products first if you want the official wording and what it covers. Erectile symptoms are a separate question with their own routes, and three articles take them from different angles: Erectile Dysfunction Causes and Care, Pelvic Therapy for Male Sexual Health and ED Treatment Options From MedlinePlus.