Why are you set on going the FHA route for your refinance?
Every lender's requirements will vary, however, you can obtain conventional financing with a 620+ credit score and possibly remove monthly PMI payments even if you don't have 20% equity. Not to mention the savings would most definitely increase by avoiding FHA.
While we'd need discuss the specifics of your current mortgage, I'd recommend a conventional 26 year or 27 year fixed-rate, so you wouldn't be adding on any additional years of payments AND just picking up where you left off, not to mention at a lower interest rate. Fact of the matter is your mortgage is an extremely powerful tool and, when structured correctly, can provide some truly amazing benefits.
If you'd like to discuss your scenario in greater depth, I'd welcome the opportunity to weigh out real options that will create both short term and term term benefits. Please contact me at your earliest convenience via phone or email; whichever is easiest for you.
Paul F. Marzolla
Sr. Mortgage Consultant