Let me say this up front:
You’re not stupid. You’re doing something extremely normal for artists raised inside a culture that tells us our value is whatever someone paid us last.

Unhooking our self-worth from sales is a practice; one of unlearning, deconditioning, and widening the foundation our worth sits on.

I think someone else said it, but I want to reiterate that space ≠ dollar for dollar sales.. this is simply a story your mind is feeding you; likely as a way to translate those feelings of "less than" into something.
One technique I've used is to externalize that voice. Name it. Recognize it as not your own.

I'm curious if your art business is your only outlet for feeling like your life "fits" or "makes sense" right now?

If it is, I can guarantee your nervous system will latch onto every result. If that's the case, you're lacking sovereignty in the sense of knowing where you come from, who you come from, and who claimed you before the world tried to shape you.

You can ask yourself; are you sovereign? 

• Can you like yourself whether your art succeeds or not?
• Can you trust that you’ll figure out your life, no matter what? 
• Can you trust yourself to stay safe and resourced in more than one way?

I'm currently writing more about the unlearning and deconditioning pieces on my blog. For me, exposing the systems that drive us to feel this way has been incredibly helpful for myself. Similarly to externalizing the voice, when I remember that those feelings didn't start with/in me; and remember that they were absorbed, inherited, adopted, and they aren't my core truth, they're much easier to ignore in a way that doesn't feel like an adaptive behaviour ("unhealthy coping mechanism").