I'd like to learn

[orochii]

Is there any way to make it bigger without making it blurry?

Start again from scratch.
Mwahahahahahahaah!

No, um... you can use Paint or any other tool that doesn't apply any kind of smooth. Or deactivate it if it lets you do so (ex. GraphicsGale). Or try changing the image color depth to 256 colours (8bit, a.k.a. indexed colour).

Nice to see your sprite developing. Here is a little thing, after making a basic outline, and then coming to the cleaning, try to make curves like this

Cleaning a line. Removing most irregularities, simpliflying the line. This is achieved by escalating the lenght of each sub-line, from small to big. It's one of these things that are easier to do than try and explain it.