3" at 25 yards is good enough to kill a deer. I've heard a rule of thumb that goes "shoot to the distance that you can keep five arrows in a small pie plate". If you are consistently shooting that size groups at that range, I wouldn't worry about it too much. Some people's groups look better on the internet, than they do in real life.

Also, do you practice in low light conditions? I consistently shoot 1 1/2" to 2", 5 arrow groups at 20 yards in ideal light conditions at a deer 3-D target (field points and mechanicals). When I shoot at dusk, that opens up to 2 1/2" to 3". I'm 46 and wear bi-focals. I don't know if that has anything to do with it. Has anyone else had that experience?