I see progress, Yannos. Keep up the good work.
Yannos, what scanner are you using? If it's an Epson, see if it improves if you scan as "Black and White Document", it works for me so maybe it will help you too.
How long did it take you? I suppose fifty pages of drawings take quite a while.
Last thing: there's nothing shameful in using a ruler, even if some drawing books say "a real artist shouldn't use rulers". I would reccomend a T-ruler for you. It's a ruler but with a perpendicular band at one side.
G'luck