I think I'm balding, but not really sure

[misterioking]

I've noticed those thin areas some years ago, 2 years to be more specific. I'm 20 years old and have a practically full head of hair, but there are those areas. If I randomly decide to comb my hair, at least 20 to 30 strands of hair fall on the sink, but I don't see any sign of thinning besides that little area. I had have no signs of recession in my hairline, maybe some thinning in the temples. Since I'm too young, some people told me to start using Finasteride when it gets worse, but I don't want to take too long, have no courage to shave it. I've went to many dermatologists but each one gave me a different answer. 2 of them said that it could be related to nutrition, 1 said it's early balding, but all of them agree that I have a very aggressive case of dandruff and this could be affecting my hair. Tell me what do you guys think and if I should wait at least 1 or 2 years before start using Finasteride (I've used it for 3 months, really have no idea if it did work)

I've put the photos in the link below, I can't use the attachment, don't know if it's related to the forum or my internet is really slow today.

https://imgur.com/a/hh3mixy

Thanks for any answer

Best regards