I just turned 25, I'll give you my two cents.
From what I understand using test below my age has the likelihood of fucking up your t-levels forever. That would be bad. But I'm on week 6 of my first cycle and I've never felt better. I'm strong as fuck, hitting new PRs, I feel my presence around people is stronger, I'm noticing girls mirin' more, I'm always horny as fuck.
I think hopping on test for cycles is definitely a good idea. I used to be a guy who believed in "hard work and dedication" but that's just bullshit. Being on test has changed my life, at least in the short term. I'm actually thinking of increasing my cycle from 12 weeks to 16 since I have three vials anyways.
But going on TRT, especially through buying from underground sources... seems like a bad and expensive idea. You also have to consider an AI as well, maybe. I don't know. I just have never really researched that. I know guys blast and cruise on a moderate amount of test per week, though I don't know if they are taking an AI with that or even what a blast PCT would be...
But I've thought about all of your reasons listed and I've always been a skinny fag until I turned 21 and started lifting. There are things you can do to raise your t-levels naturally. Lift, lose weight, avoid plastics, etc. But there is nothing quite like doing a cycle I must say.
My advice, avoid doing your own TRT. Get that shit when you're 35 or 40. Do a cycle so long as your routine, diet, and bloods are in check. If you're afraid to needle your ass, do what you can to raise your t-levels normally first. But, I'm telling you, I pin no problem now. My first time was shaky ass hands, closing my eyes, twitching... Now I just pin no problem while watching a YouTube video.
I'm no expert, or doctor. But I think doing cycles would be preferable to some blast and cruise TRT style stuff.