JW,
I been watching this thread and haven't said anything because Mr. Burchett has been giving you the straight skinny from the get-go. Eastern Woodland bows are my favorite and sort of a "specialty" for a lot of years and yours is a very nice example sir. You should, rightfully so, be proud of it.
That "thump" you feel is mostly because you have a "full" grip on the bow hand. You may not be aware that a common misconception of the NA shooting style is that they drew from the quiver. More often than not the quiver is used for storage while the bow hand served as the magazine. Meaning the hunter would very often have 3-4 "extra" arrows in the bow hand while shooting and re-load the bow from those. I only mention this because it directly affects the "grip". If your bow hand is holding other arrows and the bow you can only grab the bow with the web between the first finger and the thumb and with a "high wrist" (palm of the hand not on the bow) as well.
As evenly tillered as you are it will shoot really smooth with the "open" bow grip.....and no it wont jump out of your hand either. Looks like you not only captured the mechanics of the design but also the essence of the shooting form.
rich