On the pictures 9947 and 9548 the background is brighter than your subject, next time try to use a flash for your indoor shoot, and make it bounce form the ceiling or the wall behind you, it make a huge difference without the amateur flash look. This way your subject will be more lighted and it will allow you to decrease one stop or two from your camera (and allow you to shoot at a lower iso). I like the rusty chair look, it draw attention to the ring, I only saw the small ring on second look thought. You have a nice sense of composition, the flaws comes from a lack of technique. Of course I didn’t see all your picture but from this small sample but I’ll say that your boss was wrong to criticize so much.