For a rushed job, you did very well. I love the helmet. Looking at the pics, most of what I see wrong is just a matter of items not being positioned properly, or donned too quickly. As such, they just need some straightening out. The biggest offender is the back plate being shifted off to the left. Overall though, not bad.
As for your helmet looking "disproportionate", even though it fits you fine,
don't change the helmet. The trick for someone with a smaller stature, and/or more slender shoulders, it to
make your shoulders appear broader than they are. You can do this by redesigning your shoulder armor. Go with larger pauldrons instead of the smaller spaders you have now. Here's another good example of a girl with similar "issues" of stature, and how she and her sister (the one making the kit for her), solved them:
https://mandalorianmercs.org/forum/index.php?topic=203565.0







This girl is very slight of build, and definitely petite. However, you can see that simply making her shoulders appear broader by how they padded her spaulders, and added the fur cape, dealt with that issue. So, if your helmet fits you fine as is, don't make a smaller one, it won't fit, and will be super uncomfortable. Instead, modify your shoulder armor to
make your shoulders broader.