I think one or two private or semi-private (no more than 3-4 people in the group) lessons would do wonders for you. From the sounds of it, you may still using the "falling leaf" technique to turning, which if an instructor taught you this, he should be shot. Otherwise, it is a common safety valve for beginners (especially self-taught beginners) to use this approach, but you'll never get better using it.
Now that you have lost some weight (50 lbs, is a lot of weight to lose, congratulations!) you should find snowboarding easier, as you would expect for any physical pursuit. This is because you're not carrying extra weight that is putting added stress on your bones & joints, and fatigue to your muscles.
Don't worry about hopping, jumping, terrain park or any of that. Get a lesson or two and learn or re-learn the basic fundamentals of controlling yourself on a board: j-turns, stopping in a controlled manner, then s-turns, then controlling your speed and linking turns.
When you're comfortable negotiating intermediate terrain, then you can worry about the terrain park and jumps and all that. But first make sure you got the basics under control.