I'm a tough grader. Given the circumstances you did very well. I bet you get an B+ / A- on it.
My opinions are not necessarily right, but if they made you reconsider some things to possibly make it better, then that's all a prof can ever hope for.
Honestly, your reaction to feedback is much more of an indicator of future success. If your willing to keep moving forward all the while being open to learning here and there (on LR, a little bit of wisdom can even occasionally come out of the mouths of fools), taking criticism for what it's worth (dismissing the bad, and giving a second thought to the good), then you'll do very well regardless of the field - especially if it is what you love to do. In this, you get an A+.
I think I read on LR a quote from Josh Cox in which he said something like, "Dedication and persistence closes the gap on talent." Once again, running is the best analogy for life. Best of luck in your chosen field. And, when you're out there, keep your eyes open for the opportunity (and there are tons in which there is no specified major for) that is yours. And, when that opportunity crosses your path, go for it like it is the race of your life.