Like I said you do own it, without being registered the most you can do is go to court for a cease and desist order. If you are filed you can sue for monetary damages. You can not sue for monetary damages that would have existed before you filed, like if someone was using your work and making money before you filed, you could only sue for damages that occurred after you filed. Plus there is still the fair use doctrine, which gives you a right to use another's work as long as you accredit them and there is no significant monetary return.