Hey Hegast,
Welcome back to the sport 🙂
Good question and it’s quite common. To improve your swing you want to take the ball at the top of the bounce, and stay close to the table. Relax your arm and focus on staying low bending your knees and rotate into the ball. Use your legs and torso as you rotate into the ball, then snap your arm as you contact the ball. I think the best way to implement this is not to hit the ball to hard. Slow things right down and focus on using all the mechanics of your body first.
Try to also focus on your follow through. You don’t want to contact the ball and follow through to far, it will make your recovery to the next shot difficult. Once you have made contact with the ball try to finish the bat in front of your body and then work on the recovery. See the video link below for an example.
Is there any chance you can send us a video of yourself playing your forehand topspin? This would really help. You could upload it to youtube, set it to unlisted and send us the link 🙂
Check out this video to: https://tabletennisdailyacademy.com/videos/feeling-and-control/ this is a good way to see what I mean to develop ball feeling using a compact stroke.
Good luck Hegast, you will master it in no time at all.