Weight at draw is only one of the things that determine effectiveness. With that long of a bow and that much set, I'm concerned you might have a sluggish shooter. Honestly, it seems something has gone wrong in design, construction, tillering, or material choice.
Does it shoot hard? Have you flight tested it? Do you draw it the full 28"? Can you shoot it well? It'll likely do the trick on whitetail but those variables you mention can really mess things up.
p.s. A selfbow is one piece of wood (or other material) from end to end and front to back. You have a composite or backed bow there.