Let me give you "elderly man" prospective.
At you age (21 1/2) your physical development as male have (almost) completed i.e.
early adult transition (17–22). You will not grow taller, your wiener (sorry to break this to you) will not get any bigger,
you are done from pure body's natural hormonal development. You have entered
the adult world (22–28). Your hormones are at optimal levels to complete nature' Primary Objective (reciprocate) and live the life to its fullest.
At this stage you
can manipulate your physical appearance, however. This is based on concuss choice - either stage yourself for "fat fuck" for the rest of your life, or "lean mean machine" without having to resort to "PED" (for now).
I am not going to touch on "healing" you a are seeking, I am not a Doctor or Shaman. I am, however, someone who went through heaven and hell and can speak from personal experience.
It does not matter how tall are you. With proper diet and exercise (and hard work) you can achieve this WOW look many here are seeking (and achieved already).
As
@Jeffg353 said, why risk wrecking your hormones
right now? You are years away from the point you might consider PED. If as myself you don't have "True bodybuilding aspirations" i.e. competing, you could achieve good looks just by eating clean, right, and exercise. All this by the way will set the right conditions where you can enjoy your mid-life and even later.
If however, in your late 20, early 30 you want to enter competitive world,
then would be the right time to seek something to give you "plain field" because "the other guys doing it too"...
And there is the "other" factor... financials. You think you have the will to say "Well, I've spent XXX on HGH and don't see the gains I was hoping to have, that's it - I am done"? Most likely you will reach out for the next kit... Might be now... I hope...
Do blood work, simple as that. Come back here and lets talk. Ironically, a lady friend was telling my wife her husband lost any interest in bed, wife told her about privatemdlabs, she made him do some tests and... now he is under treatment for an awful condition, luckily discovered in very early stage. I am not saying you have issue, but many here can give you better advice once the numbers are in.