I think it really helps a lot to come into the court as part of hitting the inside-out forehand (or any very aggressive shot) and not waiting for the reply from the opponent. Anticipate the short reply by moving forward into the court before the opponent hits. Getting to the ball earlier means you can hit the ball at a high point (which means you can use more pace) and also takes time from your opponent.
When hitting the short shot, I would go for more angle than pace (I aim for the outside corner of the service box). At 3.5, you do not need a winner as much as you need a high percentage shot that is really tough for the opponent to return (forcing mistakes).
You can practice by standing near the center of the court (intersection of the service line and mid-line), preparing the racket low (to get under the ball), bounce feeding the ball low, and hitting to the outside corners of the service boxes with heavy topspin.