Hello... I have done lots of work with WC pencils...not sure what brand you are using (I find some are better than others) but a basic necessity for dry blending is the WHITE. I go through white pencils like no tomorrow...
Anyway - In general, I think the composition is fine. To help with the feeling of un-natural feeling in the flower, try adding another stalk, a bit less symetrical - but instead of a full bloom, have it in a pod, or bud.
As for the colors.. .your tone in the leaves are good.
The flowers petals need some depth..
WC pencils can be fun, but are hard. Like crayons they want to leave behind a texture, that comes across grainy or rough, and moreso if your paper has more grain to it. To help the blend and minimalise this, I use the white.
**You may have to go over a few times to get the look you are wanting, but in the end... You may really like it! If you are not sure... try the technique on a sample paper, before adjusting your picture here.
All the best!