Hi, mind telling us this location you're at when you took those shots?

Are you using a tripod? Try to use a narrower aperture and a longer shutter speed. Ever tried using a black card placed in front of your lens?

I heard that the fireworks last 30 minutes. Only worry is that the smoke might get into the frame as well.

Anyway, the event is till the 2nd of Sept. Plenty of time to shoot and improve.