For an HDR you want more exposures, for one thing. Go brighter on 2-3 more.
Second, I would search for my name and night photography. I've given a slew of tips that would help you a lot. You missed focus completely on this.
Third, I would recommend you do an HDR of something simpler. Night photography is VERY challenging all by itself, so you're combining all the complexity of that with the complexity of HDR. Quite a big jump.