Wow. I always chuckle when confronted with the hubris of thin-skinned 20 somethings who've taken three whole photography classes and has the experience of 6 years. Buddy, there's a big difference between having your friends swoon over your work, and actually producing quality stuff that earns it's place in the marketplace. You should be down on your knees, thanking Rad for taking the time and effort to try to make you a better photographer. As people have said, your work is fine, but no finer than hundreds of other 21 year olds with your experience. Every so often, I click open a picture on this forum, and It just grabs me, and I say "Wow!" It's a big leap from competent to "Wow", and few photographers make it. You've got the same chance as anyone else to make that jump, but whining over criticism meant to make you a better photographer is a poor way to start. Good luck.
PS - By the way, the recommended book is excellent.