I'm really happy that you're taking this step after having been out of work for a year. It's normal to be nervous, but remember to have confidence in yourself (you have experience, you're smart, you've made it through a very difficult year where you had to advocate for yourself a lot). Have you thought about practicing/having a mock interview with your fiance?
For tomorrow, take a deep breath before you go into your interview, smile, and just be yourself. I think sincerity and friendliness go a long way.