Depends! CEO is fine, business development is good too.
Is it even legal to call yourself CEO if you aren't a C-Corp? A basement LLC with a CEO always makes me laugh. How about Owner or Founder?
CEO of a LLC is legal if you're in sole control of the company but yeh, owner/founder is fine too. I used to call myself Founder when the company was just me.
Of course it's legal, but the "C" stands for "Chief" which has a pretty strong implication that there are non-Chief Executives in the company.
If you're not at a position to have full-time employees whose sole job is to manager managers, it's unlikely "CEO" really fits.