I do all of my stitching by hand and I think you're doing a beautiful job. With hand piecing, I get at least 12 to16 stitches per inch, but 8 to 12 is more reasonable for quilting. One determining factor in the sizes of stitches, I find, is the size of the needles.. not just the length, but the diameter too. As the others have said, consistency is important and yours is absolutely lovely.
I've seen quilts on sale in shops allegedly done by "professionals" that were not nearly as well done as yours.. some real toe hangers let me tell you. Anyone should be proud to have a bit of your work. If you're not totally pleased with it, just keep working. It will get even better as you go on.