Tradcat,
IF you are using your bones to hold your bow at full draw, you cannot overdraw. IF you are using your arm to draw, then overdrawing is nearly guaranteed or at least much more possible.
Get a solid "bone" bridge from bow hand to string shoulder, let your string arm move into your face, find your references, and there you are.
Your anchor references are a RESULT of your draw, NOT a target to be hit and then conform your body around.
Arne