Where do you live, maybe someone can offer you a mailed pkg FREE? I would ship some bridle line your way, might even with knots inserted if in the states.
my advise is to spend inordinate amounts of time insuring your lines are even.... affix all 4 independent lines to handles and pull tightly against a single fence post or well-placed tent stake, a screwdriver. Now you will undoubtedly find them less than perfect. I adjust on the leaders, not caring if they (the string strands) are different themselves.
Sight down the top of the handles, ( both perfectly aligned in your grasp) like shooting an arrow, towards the stake (insure you are directly downwind or upwind),.... slowly give slack and the longer line will droop showing itself. Bridle line can be untied and tied again (easily!), I only use knots in one strand, but each attachment point has the bridle line doubled, so if you needed a knot between two existing ones you could insert it perfectly in the virgin strand. When the tops are perfect you'll rotate the handles and work on the bottom leaders.
this process is a front end alignment to your car before you begin a road-race, you don't want that machine jumping around randomly without your commands, right?
i identify which handle goes into which hand with colored electrical vinyl tape. Now do your tuning of leaders with the handles in the wrong hand, in case one side is dominate.
do this religiously and remove a big variable..... you know your lines on the handles are ready and perfect, whatever is wrong "it ain't that
I do this frequently and recommend it to masters and newbies equally. It ha nothing to do with the wind or your kite, it's location immune.
knots should be close together, two show across my thumb nail in fact, on tops and bottoms. MY hands are not large!