It's not you. A lot of Kissaluv's got loose elastic, don't know why. Sometimes it still works ok for a baby, especially since you are using it with a cover as extra backup for a leak. I used one KL0 with good elastic and one with loose elastic on DS as a newborn and both were fine.
I am in the minority who found that bumGenius one size did not work for my DS until he was over 2 months. They are still a little big in the rise, but he wears them regularly now at 4 months (sleeping in one now, in fact).
If you were the first owner, I am a little surprised the Fuzzibunz got loose elastic since you don't hear about that quite as much, but it happens.
Don't write off CDs because of this. It happens to a lot of people, and if you need help, there are people on diaperswappers or maybe here on BBB (ask lizajane) who will replace elastic for a small fee. You pay shipping, but it's cheaper than new CDs.
Advice and commentary on living overseas
DD1 13, DD2 10, and DS 7