As I mentioned in an earlier comment, it's best to avoid filled corner sin your lines. So, more outlines like in the bottom right here, where the line segments aren't fully connected. The brain reads that as a 1px-thick line. When you have the connected corners, it reads like a 1px thick line with occasional 2px clumps in it.
Here's a good pixel lineart tutorial, it talks about both this issue and talks about how to make smoother curves, which you're also having some trouble with. There is also this more general tutorial, which should also be of use.
Lastly, you don't need to pre-zoom your art for PJ, since the site has zoom buttons. Pre-zooming such small pieces could be good as the preview image, rather than the detail file, so that it's easier to click, and then the detail file can be 1x so that people can choose whatever size they want to see it at.
Okay thanks, I will take a look at this tutorials. And I will fix this art again.