Like I told my florist I would do, I tried to make the Jello centerpieces. Unfortunately, I have to say that I somehow didn't get any pictures of this process, and I am so sorry that I can't share it with you right now. But, I will say, that it didn't come out much different from what the florist was able to accomplish.
I used a much larger vase than the florist used, and filled it with six cups of Jello, whereas the florist only used two. That alone made a huge difference, and with that I was able to get the flowers to stay down in the Jello, but that was only because I kept pushing them down with chopsticks. When pushing them down, petals kept breaking off and folding in half, and the flowers looked terrible.
So, I think this idea wouldn't work with real flowers, no matter what, so maybe I will try to do it with fake flowers that way the petals have a less chance of falling off and folding.
But, no matter what, I promise that I will take pictures next time.