I've done some fireworks in the past, and yours have come out quite similar to mine, nothing wrong with them at all. For me, though, what makes some fireworks shots is having an interesting foreground as well as the firework itself, and around here most of my local displays don't lend themselves to it because of their locations.
I used to often take the wrong lens with me. One year I went with a Tamron 70-200 and fought my way through pitch darkness to get a decent view across some fields towards the display. Aside from almost having a heart attack any time anything in the nearby hedges rustled, I found quite quickly that it wasn't anywhere near wide enough for the location. The trouble is, it's hard to guess on that until the fireworks actually start going up.