How Can I get more Power?

[David LoPan]

I've been practicing...a lot.

Anyway I have a pretty crappy set of clubs but even so I'm hitting the balls very thin (interpolate for missing irons).

Driver - 225 - 250
3 - 200
5 - 175-200
Hybrid 3 - 150-175
4 iron - 165-175
6 iron - 145
8 iron - 125
PW - 100

Is it simply a matter of clubs or is there a deeper issue here. I've had a couple lessons and I think my form is ok so I just want to hit the ball harder. (I'm not a scrawny guy either by any means)