Am I starting to show signs of a receding hairline or premature balding? (Photo)

In my opinion, you should be evaluated by a hair expert. They will do a good history and examination and determine if you are displaying signs of Androgenic alopecia. You seem to have hairline maturation. There are many good treatments for genetic type hair loss. Finasteride is an excellent drug at decreasing hair loss and possibly stimulating regrowth in younger individuals. Minoxidil is effective in approximately 40% of individuals. Low level laser and platelet rich plasma have studies to support their effectiveness. We have had good results lately with platelet rich plasma in younger individuals. It thickens the hair and decreases hair loss. Regrowth of hair is variable. All treatments of genetic type hair loss need to be continued. Platelet rich plasma needs to be injected 2 - 3 times per year hope this helps. Good luck.

It's a good idea to meet with a hair specialist so he or she can carefully review your hairline and the areas behind. Mostly likely you have some early AGA combined with some degree of hairline maturation. Please speak with an expert. 

You may be developing a maturing hairline as I see your widow's peak and that is a sign that the hairline is not receding. If you are concerned about hair loss behind the hairline, then 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, 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. This drug, however, will not stop the development of a mature hairline.