What's your drawlength? Unless it's extremely short, your set-up should be more then adequate to take elk, and to achieve a passthrough on most shots in the vitals.

In additon to what the others mentioned, check your blade sharpness. A razor sharp blade that is traveling straight forward, will penetrate the furthest. If your broadhead aren't razor sharp (can shave hair easily), then learn how to get them that way. They can dull, just pulling them in and out of a quiver. I find that very few bowhunters pay proper attention to broadhead sharpness. It matters not what they are like when you open the package. It is up to each hunter to touch them up, until sharp enough to shave with. You need to do this whenever they are shot or after being removed from the quiver several times.