Someone can correct me if I’m wrong but as far as I was aware, the wider the grip when benching the shorter the range of motion and thus the more weight that can be moved. Additionally and again I may be wrong here, but the triceps play a dominant role in the bench press and so if you have been benching with a narrower grip (consequently involving the triceps even more) then it would be safe to assume your triceps are your strong point. Therefore if you were to bench with a wider grip you would be able to lift even more than you currently do.