When going from a perfect "T" to having my bow arm at a slight angle as in the form clock I lose about an inch. I have been shooting like that for awhile now and believe it to be necessary in order for the string to stay off my body. Does that sound right?
Im no expert, but "yes"
I think your draw length should be determined by whatever anchor point you need to use in order to have your forearm in line with the arrow at full draw, viewed from the top. The most critical thing is to have your shoulders perpendicular to the target. So you want to make sure that when you move your bow arm into a slight angle, it isn't at the expense of having your shoulders open up with respect to the target.