For a quick assessment of your Meyers-Briggs profile, try WorldPersonality.com.  Another testing, using a different set of models but yielding equally interesting results, is available at OneIshy.com.  This site also offers lists of potential strengths and weaknesses for the various personality types indicated.

Now that you have a sense of your strengths and weaknesses, this article discusses how to put that understanding to good use.  There are also plenty of books and programs that can help you get acquainted with yourself in the Psychology and Creative Development sections of our new Amazon store. 

You can go even deeper into your own performing self with Don Greene's Performance Skills Inventory (PSI).  This test is specifically designed for classical musicians, and a sample inventory is available on his website at no charge.  For about $30, you'll get an in-depth and detailed assessment of your strengths and weaknesses in seven areas of competency, then you'll receive customized plans for taking action, and unlimited opportunities to take the online assessment again, so you can gauge your progress.

 
These are, of course, just a few of the tests and resources available, but they'll get you started.  Whether you've never attempted this sort of self-exploration or you're looking for a new way to look at what's holding you back, any one of these will provide a starting point.