So 8 stone is 115 lb. You are 5'4". That is pretty average for a woman. 115 would be considered a healthy weight if you are fit and have some muscle tone. You are not tall or heavy. To be useful as a cheerleader, you do need strength. To gain strength, exercise, working on your core strength and legs. If you seriously want to get down to 70 lb, you have an eating disorder or other mental illness, because you will NOT be strong enough to do cheerleading at that weight. Face it; your real goal must be to be the top of the pyramid - the star. That may not be your destiny, but if you are strong and healthy, you can be a cheerleader, so focus on that.
Please do t do that to urself it's not healthy it will b dangerous to weigh so little for ur height too it can affect your organs in the long run n fertility too, I'm 5ft 4 too and was super slim at your age I weighed 7 and half so not far off pleae don't and your so young too x