Can I do this process on my own?

3. Can a K-1 visa be extended if I feel I’m not ready to get married?
The K-1 visa cannot be extended beyond the 90 day period. The visa is good for one entry into the United States within six months of its issuance. The visa is issued only when both parties are fully aware that they must marry within 90 days of the fiancée’s arrival in the United States.  The fiancée visa will only be granted to an individual who takes an oath that he/she has true intent to marry the U.S. citizen. Though you are not required to wed, the fiancée will be sent back to his/her country abroad if the wedding does not occur within the allocated time.