You need to see a doctor for a proper exam if you want a proper diagnosis. Afterwards you can think about treatment.
The best non surgical solutions to hair loss issues are the use of Finasteride (oral) and Minoxidil (topical). This will help slow down the rate at which your hair is falling out and help with density. You may want to also use Vivscal Pro which is an all natural supplement. I hope the information helps.
Your biggest enemy is the progressive thinning leading to a balding pattern that is not evident at this point in time. The degree of thinning that you are experiencing would suggest that you should see a doctor who most likely will get Bulk Measurements of your hair to determine the degree of the thinning that you are presently having. If the diagnosis is early genetic hair loss (the most common cause of hair loss in young men), then the best treatment would be the drug finasteride which is highly effective in men of your age and may not only stop the hair loss but possibly reverse it. If you are developing a more advanced balding pattern the best test to get will determine the Bulk Measurements of your hair and this will show, over a one-year time frame, how effective the treatment will be. Once you know this information, then you and your doctor need to develop a MASTER PLAN which will define what you need to do over the years to come.