Can you take a look at the following link and answer the questions at the bottom of the sheet? Your answers will allow me to accurately model the loading and size your beam. Thanks
From my sketch, you can assume your garage is the 2nd floor
1. If the top floor of my sketch is your freestanding one story garage, which beam would it be, a New Beam #5 or a New Beam #3?
2. Is there any storage or occupancy in your attic area?