I was right where you are 4 yrs ago. All the advice here is excellent. However, I'd like to address something completely unrelated to technique, but rather physics. You even mentioned this at the end of your post.
I learned the hard way when I knew no better and tried for 3 weeks to run the course on an F1 at -15 and 30mph after free skiing it at 34mph + and -22 & -28.
I did make the course a few times on the f1 but the simple fact is there just isn't enough support underneath high performance skis designed specifically for short lines @ 34-36 mph to make skiing at 30mph any easy task.
I feel as much as you can try to make positive changes and ride balanced etc etc you are fighting a losing battle until you get on a ski better suited to support you at 28-32 mph.
A larger ski will allow for glide and balance , giving you confidence to get up over the front foot on your 2,4,6 with out dumping you over the front or skiddishly going like hell when you give it too much input. Essentially You are trying to walk a tight rope while trying to learn an already incredibly hard sport.
You can learn to move properly on a larger ski and carve a turn much easier. The ease of width will blow your mind. On this vapor You want to stay back because this is a comfortable place on a high performance ski at those speeds.
Yes, good skiers get it done when they are messing around but it's no easy task. I was accidentally pulled thru the course at 28 mph on my 66 in GT @ -22 last week. I ran it for the hell of it and damn, it was LOTS of work. I had to watch how much and when I moved to the front of the ski or it would just stop. I was always plowing water. Not an ideal situation.
Back when I first learned I ditched the F1 & changed to a carbon V. I immediately ran most all of my attempts at 30 -15 and got thru 34mph quickly. Best decision I ever made.
The coefficient x's are also awesome.
spending $ on a new ski sucks but it won't when your are progressing within a few rides.
Just my 2 cents but if I were you I'd go demo a ski designed for learning at long line and slow speeds. I think you'll be impressed