yeah that sure is a disappointment. Selfbows and stone points can be tough going at times. Just a few things I noticed though (I am an advocate for close shots with stone points) 20 ft up in a tree is a long way up. I've killed a lot of deer 10 - 12 feet high. Obviously the higher you are the higher the shot angle and also, they smaller the double lung kill zone is. Also 20-25 yards is actually a pretty far shot with stone points. Certainly it can be done, but the chance for things to go wrong increases. I shoot very close shots. I prefer 8 yards... slam dunk shots. I will shoot out a little further, but typically never over 15y and I let a lot go at 15 hoping for a 10 the next day! Most the time when I have experienced poor penetration it was due to shooting too big of points, and/or rough transitions and/or not a heavy enough bow/arrow combination. I've seen some guys on here shooting some pretty darn big points, and not always, but often times I see a lack of penetration because of it. I like bows in the upper 50's- 60's weight range, reasonably heavy arrows, my points are very very sharp 60-100 grain points no wider than about an inch and about 2 inches long at the most. very smooth, tapered, point to shaft transitions and spinning perfectly true. 8-12 yards and I am almost always looking at a pass through or pass through with arrow still inside the deer.
I experienced similar results in my earlier attempts. shots a little too far, bow and arrow combo wasn't up to snuff... points too big and too dull. Not exactly sure of your whole set up, but I would shorten your shooting ranges, make those points scary sharp & small and forget about that past bad experience. keep after it because you are on the right path! hope to see some success pictures soon! - Ryan