My bubble doesn't resemble yours at all

What's wrong? The bubble looks great.

You could lower the opacity on the fill layers a bit more, but honestly? I think your bubble is going to perform MUCH better than mine! I found mine was a bit too transparent.

Your looks super close and as Paul says, probably even performs better.

the gradient material is perhaps a little too tight, yes. If you've created that texture on its own layer, go into edit mode, select the shape with the radial gradient on it, and use the transform/rotate/scale tool to scale it up a little. I think this should fix the issue quickly.