Some of your punching power is a matter of raw strength and a plethora fast twitch muscle fibers, but technique matters a lot.

Read "Championship Fighting: Explosive Punching and Aggressive Defense" by Jack Dempsy. IMHO it contains a lot of wisdom that has been lost over time and is no longer taught by many contemporary boxing trainers.

If you read it and find it helps, could you please post your results? It might help others and would make for some interesting reading in any case.