So I am a bit of a pen fan, and I use fountain pens... They arent necessarily the solution for you, but this leads in to a really important consideration...
What paper are you using? Maybe try a better quality paper? I use whitelines:
and the paper is AMAZING. No bleed (which is also a factor of paper), thick paper, the white lines is an awesome feature, etc.
DO NOT use the moleskine paper... it is just crappy.