OP, you might change nibs. My handwriting is godfuckingawful, but if I switch to something like an italic or stub nib, it adds a certain character to my handwriting that, well, it ain't classical calligraphy, but it's actually pretty to look at.

Other tips if you do want to improve: try moving from the shoulder instead of the wrist (think about writing on a black or white board!).

Write the alphabet 2-3 times every day. That's it. Just abcde etc. I find that just doing that is enough to loosen up my handwriting.