And the answer is no! Some of my characters have some traits of mine, others have none at all. So I would say it is difficult to take my "cast" and say he/she/it is the "real me" in fictional form.
I think that is how it should be. After all the people you meet around you and get talking to will have some elements in common with you. Indeed that kind of "hitting it off at once" is often due to recognising those core elements. But nobody will have everything in common with you. Even identical twins have their differences. Each person, and therefore each character, is unique and should be recognised for that uniqueness.
So can you tell your characters apart easily? Are you sure your characters are not all clones of yourself (no matter how diluted down)? What is the unique selling point of your characters? What makes you want to write about them? Why is it Character A's story and not B's?
Plenty to think about there then...