Lot's of good information on shooting form, so I won't repeat it. That said, are you sure that your arrow is spined perfectly for your bow? I have bows that range anywhere from 40# to 50# at my 27" draw. For the bows 45# and under, the GT 35-55 typically flies stiff for me; even with a bunch of weight up front. On the other hand, a Vapor 2000 and an 1816 aluminum arrow with heavy points fly perfectly.
Claudia