I would not use that method to solve this problem. Yikes!
There's a lot of questions to answer here. Let's start with this statement:
*you have no idea how many heel side edge i've caught doing this....maybe I was side slipping*
I believe! I see it a lot. The main contributing factors are too flat a board and too much weight on the back foot. You already know why you have too much weight on the back foot (I will go "omg omg omg" and naturally just lean back hoping to slow down). My most common cure for too flat a board on toe side turns is to arch your back.
Try this exercise at home. Stand with your arms reaching over your head as high as you can get them (elbows above the ears, fingers extended). Now turn your palm to face the sky. You should feel your back arch automatically. Now bend your knees and lift your heels off the floor. You should be able to adjust the height of your heels off the floor up and down without having to move any body part above the waist. Now bring your hands down into snowboard riding position (without losing the arch) and repeat the heel raising and lowering. If it's hard, you've lost the back arch. Be careful with this exercise because if you just arch your back from a flat footed position you will just weight your heels instead of your toes. Often times I will have my students ride their toe side turns with their hands over their heads to help them get used to this. It looks goofy, but it works if you remember to lower hands for heel sides, then raise them for toe sides and to arch your back when you raise your hands. You don't need a lot of arch.
"How do I prevent myself from catching an edge?"
If you are moving in the same direction as the board is oriented and your weight is over the top of the board when you change edges you will not catch and edge. The ankle drill you mention above is an example of this concept. Changing edges while you are skidding is how you catch an edge. If you are sliding down the hill with the board sideways and flat, it's real easy for the board "to change edges" to the downhill edge and "Wham!" happens. You prevent this by engaging the uphill edge.
The problem here is that a catch 22 is involved. If you're going to fast (OMG), you're going to weight the rear foot. If you weight the rear foot, it's going to start skidding into being the front foot. As it does that, you will start losing your uphill edge engagement and transition to flat board. Which means you'll start going faster and do a bigger OMG. Repeat until you crash.
In order to break this cycle, we need to do two things: get the speed down below OMG level and start turns with a forward movement. If you watch first timers fall when they get off a chairlift, it looks like they sit back as the reason they fall. What's really happening though is that they stand up, the board starts moving down the hill and they don't move with with the board. The board gets ahead of them first, then they get afraid and finish the sit. How do you fix this? Everything has to go forward after you stand up. The way you were taught to turn (board twist, initiate with the front foot first) is designed to encourage this movement automatically. But if speed reaches OMG level, it's easy to lose it.
So how do you stop overweighting the rear foot? Slow down! How do you slow down? Either flatten the terrain you are on, make the snow slower, use more edge or turn more. Oh if we could only go riding on powder or slush days, but at least be aware that on days when the snow is (ahem) "fast" we should be seeking flatter terrain. We've already covered how to get higher edge angles. How do we turn more? The most basic form of this is to slide the hips forward so that the front leg is bent more than the back leg. Going straight down the hill, you will find that this is impossible to do until you are more experienced. But going across the hill at a constant speed, this is something you can do If you can track across the hill (aka traverse), you can rotate your feet so that the board noses uphill. If you then do board twist before you come to a stop, it's much easier to incorporate forward movement so that engage the downhill edge of the board above the fall line and carve the turn until that new inside edge becomes the uphill edge. At this point if you've let the board get ahead of you, the back foot will slide downhill of the front foot and you're in trouble again. But if you've slowed down enough before the turn started, you won't have accelerated too much during the turn and you'll be able to stay centered enough for the back foot to follow the front foot and finish the carve until you're drifting uphill to finish the new turn and start the cycle over again. Once you've trained your brain that you don't have to weight the back foot to slow down (it is an option, but it does not have to be your only option), then you can get comfortable with speed and stop finishing your turns going all the way back uphill. But until you can trust that the board can turn you and that turn shape can control speed, you can't break the catch 22 of skidding to finish your turns and the risk of slamming on a flat board. If you can't get enough weight on the front foot to hold an edge and traverse across a slope, find a flatter slope until you can.
I'll also bet that the final piece of the puzzle is that you are not flexing and extending enough. It's quite common for new riders to stiffen up when they go on steeper terrain. Flexing and extending the legs is a key movement that enables getting turns started. This movement is supposed to be another natural result of learning to start turns via board twist, but it doesn't always happen. One drill I use to help increase vertical movement in the lower body is to ride holding your knees, then touch your hands to your shoulders briefly to change edges, then return to holding your knees. When you can do this, change to holding the tops of your boots (1/2 way between knees and ankles) instead of your knees. Advanced riders should be able to do this drill holding the tops of their toes or touching the board in between touching their shoulders. This simulates the amount of movement used in moguls and steeps.
Way to go girl! I'll be looking for you on the Hobacks at Jackson!