awesome...thanks for the video MR!
^OP, it's good to make the distinction between muscling and what you're doing, which is spraying. You aren't muscling - your shot has great potential because you're getting what seems like very easy racket head speed (i.e. power and spin) through being loose, but it's a matter of controlling and focusing it to get consistent.
The reason why it's not consistent? Any ball waist high within 3 ft you kill, but for everything else it seems like you don't care enough to move to. So you take a couple of late steps or jump to adjust, and then proceed to kill it again. If you hit softer your hitting to picking up ball ratio will skyrocket, and you would be able to control your shots better.
Adding to the good info by mightyrick about swing speed, I'd suggest you spend a LOT more time - like 30 minutes of your hitting session - hitting from half court with the service line as your baseline, with a shorter, earlier takeback and consistently 3-4 feet over the net. You will quickly develop more feel and see what kind of swing speed will work for you.
examples of this:
When looking for your hitting partner's next shot, NEVER stand straight up and never let your heels touch the ground. Hitting and weight transfer during the shot is another thing, but remain on your toes, alert, knees flexed, weight slightly forward, while looking for your next shot.