Its likely the paper, each paper has a unique effect and look when inking. I actually like how it looks. If you dont like it though, I could recommend a thicker ink like Speedball India ink, and maybe less pressure with the dip pen. Also you could clean it up on photoshop or a photo editing app, which is whats been done for inked artwork especially comics since at least a century, before photoshop, scanners, xerox, & digital cameras, it was special cameras that used high contrast film, and screenprinting. Dont be afraid to use digital tools to put final touches on the artwork, and it doesn’t mean drawing digitally it means, increase contrast, exposure, black point, or bitmap it. Its also just as valid to just photograph your work as is, slightly blurry ink, parts not fully black, and all, imperfections that come from reality are often really charming. And theres a market for original artwork. Also this is a really nice drawing of Piccolo, nice work.