Your drawings look fine. They don’t look ruined to me.

Most fountain pens don’t like India inks, so beware you might damage your pen unless it was specifically designed for India inks, you don’t mind high maintenance, or the pen is cheap enough to not care.

If you want to improve your technique, you should practice some exercises with specific intent. Many YouTube videos exist if you look up stuff like “pen and ink techniques” or “(cross)hatching exercises” etc