You have all it takes, craftwise.
Inferring from your chaotic nature, maybe what you need is to be strapped to a chair with no drawing instruments nearby and reflect on things you like, what is an interesting (non-visual) idea, try to come up with a setting (it doesn't have to be fleshed-out, just evoke a sense of lore/backstory).
Why are you holding on to your pen like that? I'm just giving ideas. No... not under the sofa.
After you've thought a bit about it, you can start sketching ideas. Iterate, make the same head with 3 different haircuts, decide which one is the best. You are trying to come up with something that:
- Fits the idea;
- Looks good;
- Is fun to draw over and over again, otherwise it won't be a good OC.
Of course many people design straight from the visual element and might come up with a story afterwards, if you keep the third item on the above list in mind, you could try that as well.
Worst case scenario, you design a character whose nature involves her changing of design every other drawing, while keeping some key elements that still say "it's that character".
I also struggle with drawing the same thing more than once, but a design that speaks to you helps a lot.