Hey Michael, yeah this can be really frustrating I know! I think the best way to practice doing a proper topspin shot on both sides in a match is to set yourself a fairly low target, for example I’m going to make sure in this next set I play at least 2 full topspin shots on my backhand and then 2 on my forehand. Then the rest of the points just play how you feel comfortable and gradually up the target so you are trying it more and more.
Usually it’s just the fear of missing and making mistakes that holds you back, and wanting to win of course so being a bit more careful with your shots. So bringing in these shots slowly I find helps.
Also if you practice trying to do lots of random drills where you don’t know where the ball is going so you get used to playing a full stroke even when you’re not always in the perfect position.
Hope this helps and let us know how you get on!
Dan 🙂