Speaking as somebody who has worked as an editor and who teaches writing at the local university, any author will almost always be the worst editor of their own work. The problem is that as the author of the prose, you know what you were trying to convey in that prose. So, you'll read it into the prose regardless of whether it communicates it or not. Every author has this problem.
That said, there are two tricks that can mitigate this problem when you don't have a second set of eyeballs:
Set the chapters aside for a a month or two - long enough for you to have forgotten the specifics of what you were trying to communicate in the prose - and then come back and edit it. That will minimize the degree to which you're imposing your intentions on the prose, as opposed to picking up on what it is or is not managing to communicate.
Read the prose aloud. It's amazing just how much your ears will pick up that your eyes won't.
As I said, these won't get rid of the problem entirely (for that, you'd need to not be the author of the work), but it should reduce the number of mistakes you'll make in the edit as a result.