My roof has virtually no overhang (2-3") and I would like to add soffit vents. Is there a way to add soffit vents without extending the rafters to create an overhang?

Do they have to be soffit vents? There are several other ways to vent a roof including... ridge vents, vents along the rake edge (if your roof is a gable and not a hip), and mushroom vents. These might be some options.