are they resting on your nose at full draw? 1.5"es sounds like its plenty far forward but heck if ya have to I'd move them even a tad bit more forward or get rid of the high backs. Another idear would be to turn your head more towards your target.

I am leary of turning my nocks for clearance reasons. You can just as easily get bad arrow flight readings due to feathers themselves as you can to vanes. It's not as bad however it's easily enough to booger up broadhead flight. Add in other factors (ie bad release, torque, wrong spines etc), and it stands to reason people have a tendancy to live with poor arrow flight.