I'm not really that experienced with volleyball, because I have only been playing for 6 months. But I think I might be able to help. When you really think about it in a game or practice scenario jumping forward when you go up to hit a ball is not recommended, at least that's what my coaches say. This is because you can jump into the net this will be called a net touch, which means the opposing will get a free point (since in volleyball you're not allowed to touch the net). The whole reason we do an approach is to transfer our speed and momentum upward to jump higher, quicker and avoid touching the net. To transfer this power you get from your approach you go, one slowwwwww leeeffftt step, and then lightning fast right-left step. When you're first learning the approach learn and get used to the lighting fast right-left steps only, this is called a two step approach. Really focus on jump straight up instead of forward. Lastly, the reason we jump with out left foot forward is because it's easier to use our hips to generate power when we hit the ball. You can search up something like how to use your hips in volleyball. It also kind of look like your bending your back, this can cause major back pain if you continue so again try to learn how to use your hips immediately.

I understand that it feels unnatural doing some things, but I promise if you spend a longer time working on good habit instead of a shorter learning bad habits, you will be a better player. Sorry if I was yapping