It is more of like a typographic illustration than a typeface.
Your G is distracting, F is too light, Looking at your overall design; C look like O.

I designed my typeface by modifying a few san-serif typefaces.
Nah, not a good idea.

I designed my typeface by modifying a few san-serif typefaces.

I don't recommend that. For experimental purposes or for reference to learn something out of it, fine, but if you are going to create your own typeface, create it from scratch. That's when you really learn a lot and become a better type designer from that. Also, it gives your face something that is a necessity: originality.

New typeface ideas aside, this makes a beautiful poster.

Cut your C & G at an angle to keep them easier to ID. Unless that's not your idea. I agree. It's pretty.

But we are all guessing about your intent. Give us more background and we are less likely to leap to the wrong conclusion.

Hi guys, thanks for the comments, the typeface is actually designed for a type poster of one of my school project, definitely i am aware of using someone else typeface to make it my own. I am trying to give more originality to my design now. The attached sketch is my original initial idea. Anyway thanks again for all the comments.

The thing that seems to stand out that could use some tweaking is the scribbled lines that are part of curves, like in the C, D and G. I wish they would follow the curve better, they seem a little stiff, especially for scribbles. I might also suggest instead of the scribbling, you try hatchmarks and cross-hatchmarks, something a little more refined and consistent.

I agree with Stephen; tis a fine poster.