Tannia,
Don’t worry about the terminology. Some situations are confusing: for example a proton / anti-proton interaction is an interaction between two nucleons (nuclear particles). They unavoidably annihilate before they can go through any other reaction. I knew what you were talking about, sufficient to follow your thoughts.
The relative energy release between Nuclear Reactions and Annihilation are much greater than you think. The classic deuterium/tritium fusion to Helium and fast neutron releases about 18MeV (had to look that up), and is one of the more energetic reactions. Annihilation of the same mass of nucleons releases about 5GeV (250x more).
In practice the question for Amarrian ships is what the antimatter fuel production looks like - it’s not like digging uranium out of the ground and purifying it. Antimatter takes a lot of energy to produce (as much as it releases plus’s losses). I can imaging huge stations close to a star, using solar power to form antimatter for feeling space ships and the rest of the Empire. Bottled sunshine in golden hulls.