Is it possible that I am masturbating too much?

You should be just fine.  There really is no limit on this that I am aware of.  You sound like a typical teenager to me.  You aren't the only one doing it at least that often.  Don't believe it when everyone around you say they don't do it.  Almost everyone does at some point in the life, most do it throughout their life, and they really do it as puberty finishes its course.  The amount varies a great deal of course.  At your age, your libido is probably going wild!