You are capable of smashing the ball hard. It is probably the fear of missing that causes you to hold back. You just have to tell yourself going into a match that if you get a sitter, you're going to smash it, hit or miss. Judge your success based on making good contact with the ball and not "hitting scared", instead of judging your success by whether or not you win the point. As you hit more of these shots in matches, you will make more of them. And of course, this is something that can be worked on in practice as well. Best of luck!
