Ok, I've found a way to simplify my formula. If you have a Pokemon with IVs in the stats you want and another pokemon with similar IVs, here's a calculation you need to do for the %chance of the baby having ideal IVs...
First, determine how many IVs you are looking to be passed down. One stat is 5/6, two is 4/6, three is 3/6, and so on. Then, create a simple chart with the IVs of the pokemon...
atk1/satk1/spe1
atk2/satk2/spe2
or
31/31/31
x/x/31
The chances of getting all 31's here...50% chance for the first set of IVs to be 31, 50% chance for the second, and 100% chance for the third. Take all those percentages and multiply it by the starting fraction--3/6*.5*.5=12.5% chance. The chance of passing three 31's with one flawless and one garbage, or 31/31/31 and x/x/x is 3/6*.5*.5*.5, or 6.25%. Two 31's and a garbage and two garbages and a 31, or 31/x/31 and x/31/x is the same, 3/6*.5*.5*.5. The most important part is the initial fraction, while everything else is just 50% chances. If you only want to pass one IV, the chance of the Destiny Knot choosing in one of its five passes to be that IV is 5/6. This decreases linearly, which makes it easy to find the chances and thus the ~average number of eggs at time needed.