Any endeavor is better with practice.
When you are the one quilting it, there really are no rules.
Typically, you may have heard that with stippling, you should never cross over a line. That is a very nice rule, but this is one rule you can do anything you want with ...
I studied your quilt in the first picture, and I studied your close up and don't see any reason for your discontent except that we are always hardest on ourselves.
If the quilt is complete, balance of quilting isn't really an issue, since it looks to me that you straightlined in the checks and stippled in the background. That is your creative license! Take it! It is a good thing!
I noticed that your stippling as a few larger open spaces in it, but I thought it was an excellent design element.
You need to realize that most of the people who ever see your quilt will never know that you did anything different, because they don't know any standard - - they simply know that they either like something, or they don't ... and, they don't have to have a reason for either choice.
A weakness of diligent persons is we have a tendency to be very harsh with ourselves. We know every place the stitches are not exactly right, where we zigged left, when we should have zagged right.
Bottom line - - quilting is to hold three layers of fiber together so that the middle one doesn't shift to the bottom of the whole ... any beauty we can put into the utilitarian value of a quilt, that is just a bonus!
As I said before! You have no where to go but up ...
As far as asking for critique on this board, trust that the members here love their art and practical applications ... their main job is to encourage and share what they have learned. Thus far, you have gotten very honest feedback from the quilters because more than anything they want each of us to succeed and enjoy the process.