I just want to know if there is any way I could register my business as an LLC without being an adult.
While most states do not specify a minimum age in order to form an LLC, most states do specify a minimum age in which one has a capacity to contract and that age is 18.
Here's a good explanation of capacity to contract at Wikipedia.
It would be difficult if not impossible for a minor, acting alone, to create an LLC without a capacity to contract.
Although, it could be quite possible that a minor could go through the machinations to form an LLC without ever being challenged on their age. I don't recall ever being asked my age when I created my LLC. It would be interesting to see what would happen if such an LLC were created and then the minor disaffirmed the LLC filings or any of the contracts to which the LLC was a party that bore the minor's signature.
I have heard of suggestions elsewhere that a minor who wants to own an LLC have it owned by a trust where the minor's parents are the trustees until a specific age is attained by the minor, at which point the minor becomes the trustee. This would allow the minor to have an interest in the LLC that is managed via the trust. The trustees (the parents) would sign contracts for the LLC via the trust giving the contracts enforceability.