Will my shelf be strong enough despite one of the brackets being in drywall anchors?

Question

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!

Answer 1

part 2 - aligning the shelves.

Adding washers between the lower-shelf and the bracket will help a little now, but the wood shelves will move over time, likely at different rates.

You can also screw a metal strapping plate under both to secure them together. This will be visible below. If you choose to strap it on top, that can interfere with sliding things on/off the shelf.

Instead you could secure a thin strip of trim to the front, which will provide alignment and some additional strength. If mounted a couple millimetres higher, can also act as a safety ledge to reduce things falling off which can be an important consideration if this door is your only exit from the room.

Ideally you would have used one long shelf not two shorter ones, but that's not always possible. And the joint should have been aligned to be over one of the brackets. I'd have chosen two joints-over-brackets instead of a single unsupported butt-joint.

The main issue is that subtly-different loads there will bend each shelf different amounts, causing the cantilevered wood shelf to move visibly. It doesn't take much to be a visible difference.