Noodlers Ahab and creaper pens have ebonite feeds which can be heated and remoulded countless times to make them feed faster or slower with the ink. You can also pull the nib and feed out of the pen and adjust which is out further which changes how fast the ink feeds... a good pen designed to be played with... You can also put other similarly shaped nibs into it which is cool if you have old flex pens with quality gold nibs etc.
Goulet pens have some reviews and videos worth watching on the workings...
Despite I don’t see my name in your list I find your hand writing very nice.
I know that fountain pens can produce nice writing but if you’re looking for very thin hairlines and bold downstrokes, try with a dip nib and with iron gall ink