This is an example of the confusion many have about the difference between "conventional" and "conforming" home loans. A "conventional" mortgage is simply a home loan that is not backed by the government. So unless your mortgage is an FHA, USDA or VA mortgage, it's almost certainly a "conventional" mortgage.
(If your loan is government-backed, you don't need HARP, because all of these loans have their own streamline refinance programs, similar to HARP.)
HARP refinances are strictly available to borrowers with "conforming" mortgages. These loans get their name because they "conform" to guidelines established by Fannie Mae or Freddie Mac. All conforming loans are conventional, but not all conventional loans are conforming.
You can find out if yours is backed by Fannie Mae or Freddie Mac by using a simple online lookup tool. It's right here at