Yes, you'll never feel quite right after taking a cycle of anything. Its not because you are messed up or have low test. Its because being enhanced feels better. And there is really nothing you can tell your doc to justify putting a 20y/o on prescription test. Admitting to steroid use and having it in your medical record IMO, is also a mistake. For insurance purposes and for other reasons. Unless you are dying, in which case, yes, tell them the truth and get help.
BUT:
I know HRT seems like a good idea now, but it's a mistake...Plus, barring a really bad doctor or a pituitary tumor, your doc just isn't giving a 20y/o HRT. But you want what you want, as we all did at 20. I understand, Ive been there and went ahead with some horrible ideas...and paid for them. Live and learn.
Unfortunately, how bad you want it doesn't matter, because due to your age, your Doc will try months testing to define the problem and then months of everything else but test, before giving you test for life. Remember, Bro, she/he has to answer for putting a 20 year old on HRT. They'd rather just let you hang than risk their license unless you have a pituitary tumor or some other condition that they can clearly define and justify. So, you'll likely be undergoing some brain scans to check for that. Then clomid/HcG therapy. Which could give you breasts in the meantime if they decide not to allow you an Aromatase inhibitor.
The good news is, it's really likely that you'll bounce back with some Clomid and maybe HcG, or even nothing at all. I say all this stuff, Bro, because I did some REALLY dumb shit at 20 too, followed by ZERO pct and bounced back fine...eventually. I felt like shit for a solid year.
But at 23, I was as big and strong a I ever got, without AAS. I was pudgy sure, but massive and strong. Just get some good PCT and wait it out. At 37, it's different and now I do use AAS for HRT and enhancement.
A little 5 weeker of a prohormone may shut you down at 20, but you'll recover.
Good luck!