Is this how a bustle looks?

That looks as expected to me. There are all different types of bustles and the attachment (hooks, buttons, etc.) placement will depend on the individual dress, but there will always need to be something to attach all of the skirt/train fabric to (and it's heavy!), so the fastening can never be truly invisible. The good news is that no guest will look at you THAT closely.

I'm not familiar with bustles, but if you look at this picture, it looks the same. The only thing i might suggest is maybe changing the buttons for matching ones to what's already on your dress. That might look a bit more cohesive!

There are definitely some ways to do a bustle that are less noticeable. My dress had a white hook where you have buttons and some threaded loops where you have ribbon loops. I don't have any pictures of it but you couldn't see any of the attachments without really looking for them.