What is my graduation date?
For most institutions, the degree date is the day that the university actually hands out the degrees, not the date that you fulfill the requirements for the degree.
At all the universities that I am familiar with, this happens only at fixed times of year, and your degree will be on the first such date after you fulfill the requirements and submit the necessary paperwork. For example, my alma mater has three degree dates per year: people on the standard schedule graduate in June, and off-cycle graduation is offered in September and February.
I'm sure there are institutions that do not work this way, but in the US at least it seems to be fairly standard to have fixed degree dates.
In either case, you should be able to readily find this information on the webpage of your university's registrar's office or equivalent, like the pages I linked above.