I just put up some shelves using brackets from Home Depot and Canadian Tire. You can see them in the image below. The brackets themselves are rated for much more weight than I'm putting on them (like a thousand pounds each or something).
All the screws for the brackets are securely in studs except for the two centre brackets on the top shelf (i.e., the bracket over the door and the one to the left of that one). There weren't any studs around there that I could find (this wall's stud situation is very confusing). The screws fixing those two brackets to the wall are all fixed with these EZ Anchor Twist N Lock anchors, which claim to be rated at 75 pounds each. Each bracket is fixed to the wall with three screws in a vertical line.
My question is: How worried should I be about the strength of that upper shelf, particularly the parts held up by the drywall anchors? There's no recognizable wood to screw into above that door that I've been able to find. (I spent time looking up how studwork around a door is supposed to look, and couldn't make sense of what my stud finders were telling me).
A second question: As you can see, the two pieces of wood that form the top shelf don't line up perfectly. I believe the bracket above the door is just a fraction lower than it should be. Given that I can't just move the bracket up a little bit, is there a good way to fix this? I was thinking of trying to slip some washers or something between the shelf and that bracket.
Thanks in advance for whatever advice you have!