I have an lazy eye with +6 farsightness. my dr. suggested me wearing contact lens because she said glasses will create inbalance for me. is it true?

Depends: A "lazy" eye has lowered vision because the brain has learned to ignore its image. One cause of this is an eye significantly hyperopic compared to the other which usually causes it to drift. The brain then learns to ignore the central image from that eye to prevent doubling. The contact lens will help IF the vision is good in the lazy eye. In most cases it will not matter.