I'm no expert but I read a good amount. It looks like you used a template, so that's good. Glass will chip like that, it just looks like you had a large chip. Overall it doesn't look that bad to me, just the one part seems a little larger of a chip.
I used a corded drill that has a side handle, and is very stable to drill straight. I've read that clamping another piece of glass to the back side will minimize chipping at the end of the cut. Don't apply much pressure and let the tool grind out the glass slowly, especially slow and delicate near the end of the cut.
I set my hose sprayer to a trickle spray that kept constant cool water on the cutting surface. Also the water flow seemed to wash away the glass particles.