maxfit,
The key here isn't using your eyebrow as an anchor point, the key is to have two, or better three, anchor points. This does two things, first it helps ensure that you draw back the same amount each time, and second that your head (this is where three becomes important)is at the same angle each time you shoot which keeps your sight picture consistent.
You could anchor with one finger on your canine tooth, your thumb joint touching your cheekbone, and your eye looking down along the top of your arrow shaft and have a consistent sight picture every time. Just pick three points that work for you.