While you should not have taken Dbol at 16, if it was only for 4-8 weeks - that probably has nothing to do with how you feel now or your hair loss.
The hair loss could be genetic - there are men that start thinning in high school.
Get off the Finasteride, eat a healthy diet comprised of natural, whole foods, and do calisthetics, jog or walk every day, and read some good books.
Don't live your life in fear of Covid-19 or anything else. At your age, your body is HIGHLY resilient and can bounced back from practically anything. The best thing you can do it feed it well, exercise it well, get 7-8 hours of sleep every night, stay away from ALL drugs, and acquire knowledge and figure out what you might want to do for the rest of your life. That last point is the hard part. Set goals that you can focus on achieving. Make them realistic and then commit to accomplishing them - never give up. Once you've completed a goal, make a new goal that represents progress toward your purpose or mission in life. Always make the goals more intensive or challenging.
I am a Christian and believe in my Lord Jesus Christ, so for me, my ultimate mission or purpose in life is to serve Him, and to give Him glory. How exactly I can best do that with the remaining years of my life - I'm not totally sure about, but at least I know that much as I sort things out.
Figure out what really matters to you.
Also, at 18 your hormones, brain development, peer pressurve, parental pressue, life pressures - are going to have you mentally up and down. Deal with it like a man and be resilient. You can do it.