I have some recommendations here. When it comes to fountain pens and small writing, many factors come into play. I write small and tried many different Fine (F) and Extra Fine (XF) nibs on quite a few pens. I can say for certain that every single F and XF was slightly different across brands. The paper I wrote on and the ink it was filled with also made a difference. I found a Lamy XF to be a bit to broad for my tastes on, say, Moleskine paper but that same nib, pen, ink was perfect on Rhodia paper. Furthermore, I have found that Pelican 4001 and Noodlers ink are thicker and, therefore, produce a truer line than other inks.

If at all possible find a way to try different pens, paper and inks. I know I pen collector with lots of pens so I had the advantage of trying different things and getting lots of advice and help.

I ended up purchasing a Namiki Vanishing Point with a custom XXF nib from Richards Pens. It was a little costly but it, combined with one of the two inks mentioned above, gives me the best results on anything I write on on a regular basis.

I know it is a lot of info but hope it helps.