Lamy comes in fine/extra fine. But, a big factor in ink pens is the paper you write on. Some (lower quality) paper sucks ink, and the lines become wider.
Also, I've heard that fine nibs tend to wear out faster because there's a smaller area in contact (same pressure, so larger force on the nib). I've gone through a couple of nibs a year for my Hero pens, in school days when I used to write a lot of homework.
I'm also looking for Lamy extra fine nibs to buy.