Punch harder during matches or sparring

I've been boxing approx 8 months now, and I also do some strength training to capitalize on the important muscle groups (core, back, lower body).
I noticed that I've developed some impressive punching power on the bags - almost as good as the more seasoned fighters at my gym. I am even certain that I punch much harder than all of the other guys who started at the same time that I did.
The problem is, when I spar - I have trouble applying that power. Obviously, punching a bag is easier cuz you can concentrate on your form and delivery without worrying about movement and getting hit, but theoretically, a well timed punch at the right moment should be no different between a bag and a person.
So i'm thinking my problem is mental - perhaps i'm afraid to commit to the punch?
I'm a monster on the bag, but in the ring - i'm all speed & technique, no power.
I've dropped guys a few times with body shots (mostly straight punches), and my jab is well developed (being the usually shorter fighter), but my power shots (hooks to body and head) and straight right to the head are nowhere near their true potential.
Any tips for getting in touch with my inner killer?