Question For Singers?

Okay, well I have been in choir/chorus for a long time, and I absolutely love to sing. The thing is though, that I have been bounced around from place oto place so many times that it has been hard to "find my voice". For example, one year my choir instructor had me singing b, but now I am beginning to realize that I do not sound good that low, and it is not as comfortable. I am now more comfortable singing tenor, and it sounds and feels a lot better. Why the sudden change? Is this normal, or did I just finally "find my voice"?