Fishtailing can be caused by spine or centershot, in addition to torque. Don't worry about lining up your fletchings with bh's, that doesn't make any difference. If you are spined correctly, I'd make minor adjustments to your centershot and see how it does.

Do your field points shoot with your broadheads? Have you shot through paper to see what it looks like? What rest are you shooting...and how long are your arrows?