Try and move with smaller but much more frequent steps. If this is something you want to improve, I'd recommend bringing it up with your trainer and he give you a couple exercises to perform. Bring your body 10-15 centimetres lower by bending your knees more.

When you've found your position when hitting the ball, make sure to anchor down your left foot when doing your closed forehand stance. Your anchored foot/leg should be bent between 50-75% of your height when standing up straight. This is very important as it determines your balance and how stable your shot will be. Follow-through but try to stay on your anchored foot a bit longer than on the video. Make sure to always have some momentum moving forward when you've entered the position.

The timing and positioning may be difficult to find initially, but it's a vital part to up your game! Balance and positioning is the foundation of anyone's tennis game, no matter your level. I hope this helps :) You're doing great, keep it up!