Need Some Advice: Thinning Hair.

As the title suggests, my hair has been thinning for the past 2 years (I'm 21 now, if that means anything). I'm not bald, or particularly close to it, but there are some patches on my head that're quite thin, to the point where it's starting to get concerning. Looking for some advice for anyone who has been through a similar experience.

I tried looking around, and frankly there is so much suggesting so many different things it's hard to know what treatments actually work. So I would like ask from anyone who have been having similar issues, or anyone who knows anything particular, what treatments are available that can actually help?