An "identity" is much more than you are making it out to be, and if you knew your entire identity you might see that you are happy with some of it, and that you wish to change some of it.
"The concept “identity” does not indicate the particular natures of the existents it subsumes; it merely underscores the primary fact that they are what they are...
"A thing is—what it is; its characteristics constitute its identity....
"“Character” means a man’s nature or identity insofar as this is shaped by the moral values he accepts and automatizes. By “moral values” I mean values which are volitionally chosen, and which are fundamental, i.e., shape the whole course of a man’s action, not merely a specialized, delimited area of his life . . . . So a man’s character is, in effect, his moral essence—his self-made identity as expressed in the principles he lives by." http://aynrandlexicon.com/
All the principles you have adopted by which to operate your life; all the meanings behind all your friendships and enemies; all the character assessments you have made about other people; in short, all the things on the proverbial and metaphoric "list" that they say St. Peter will be dogmatically ticking off when you go through the Pearly Gates, are part of your identity.
Of course, you can fix the bad things and add to the good things and make your "identity" the kind of thing that people will take an hour to praise at your funeral.
What you seem to be asking is, "Can you have certainty over the values in your life, the values that create and maintain your identity?" Yes, you can, but first you must decide what your principles are and then decide to practice them in all your affairs. The more you practice them the more confidence and certainty you will have, until one day you will know that your identity is cemented into the form you wanted it to be.