Help me please

[Goose4]

Hi guys, im new to the forum and im looking for help. i am 21 years old and my hair is thinning. My grandpa started loosing his hair when he was 16 years old so i figure i am getting it from him. my hairline has receeded back a bit and so i decided to shave my hair nice and short.( i am also trying to become a cop so my new haircut suits the job :P) unfortuantely when my hair starts to grow back and i let it grow a little longer, you can tell its gotten to be pretty thin on the top and crown. I need help, i dont want to take anything that will give me bad side effects. Can you guys give me any advice about anything I can do to stop any further loss/thinning, and possibly regrow? I have read lots about histogen and other things that may be in the near future that look promising. But until then what can i do?
Also, if you know any more about histogen and their advancements and possible time lines let me know.\

I really appreciate any help from any of you.
Cheers,

Goose4