Stay at it Poppy,if You push Yourself and get tired Your over doing it and need to take a break...You need to get good and accurate at 30 and 40 yards then move out to a further distance gradually.Be sure to use the same weight broadheads as the field points you target practice with.
My God Woman...what are You planning on shooting from 50-60 and 70 yards?
My max is 30-40 yards using a Jennings Rackmaster Bow set at 55-60 pounds and I'm Hunting Deer and possibly Turkeys with the option of putting an arrow into a Coyote every now and then!
Personally I would have a D-loop put on your string and use some type of wrist/hand release to keep You centered on the string for more accurate shooting.Buy yourself one of those bright yellow bag targets and simply hang it up between 2 steel fence post by wire and shoot at it.If Your planning on Deer Hunting I would also try shooting from an elevated platform or tree stand if possible to get an idea of shooting downward at a target/animal.