We actually just say "look in the mirror". It's understood that what we see in the mirror is our reflection.
"I look at myself" sounds like a better translation. Your suggestion of, "I see myself..." sounds like a translation of, "mi vedo..." , don't you think?
Because one does not "look oneself" in this sort of context in English. One however "looks at oneself". In fact, when you are viewing or trying to view/watch/observe anything with your eyes, you look AT that thing. "At" is required with the verb "look" in these cases. Of course, verbs such as "look for", "look like" mean something very different.