My age is 18, I'm male - is hair loss at my age is normal?

Technically, hair loss is normal at any age......up to a point. "Old" hairs at the end of their growth cycle are constantly being shed to make room for new hairs, at the rate of 100-150 hairs per day. If you are losing more hair than that, or if new hairs are not growing to take the place of the hairs that have fallen out, you may be one of the many young men who are affected by genetic hair loss that can progress over the years to baldness. You should see a hair loss specialist who can properly evaluate and advise you.

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 might 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