It looks so very soft, almost like felt or velvet. The closer/right? arm seems a bit thin, but it's a great pic, and the shading on the shirt/chest is incredible.
Your teacher must be an a snob. My philosophy is, art is for fun, if you can paint the Sistine Chapel perfectly, but don't enjoy yourself, what's the point? It's just another lousy day's work if you hate doing it.
I've been known to use my finger as well, for smudging and shading . . .
Flippin heck, i love the tones you've used for the flesh and the marks you used to create the movement of the clothing. This was your first painting?!?! Gods your so talented!