Not a rare issue you've got there by a long shot. Once we get used to redirecting the ball from a stronger hitter, it gets tricky to get the same bite and control on our own shots when the incoming ball is flying slower than usual. It takes a bigger rip at the ball to add the pace we want, but that bigger swing typically comes with the tradeoff of less consistency.
Consider that when a strong opponent hits a harder ball toward you, your own swing timing is in sync with that incoming ball. If the ball takes longer than expected (or preferred) to fly into your hitting zone, it can be easy to swing a little ahead of the ball - that's a control killer. That's why the idea of deliberately moving the feet is key for proper positioning. Can't sit back and wait for that slower ball to fly into your strike zone.
Sometimes taking those slower balls on the rise can be a big help, but you need to get confident with that sort of shot and also get used to both recognizing when you can use it and how to move to the right spot in time to hit it well. It requires your forward swing to start ahead of the ball actually bouncing in your court.
One of the tips I spotted in Tennis magazine that actually stuck in my brain for more than a day addressed the issue of hitting a slower ball. The cue was to remember to never add more than about 5% pace to most any ball you hit. It's not too tough to put a little more pepper on any ball with average pace, but teeing off on a marshmallow of an incoming shot is too often a recipe for a donation to your opponent's point fund. This general thought has been helpful for me and I've also repeated it to a few of the kids I've coached to help them keep different shots under control.