First of all, why would you be taking Prozac and Lexapro at the same time? Are you sure that's what you're taking? It would seem to be very unusual and perhaps not safe to take two ssris at the same time, so I'm wondering if there's some mistake here. As to the gingko, why are you taking it? Are you on any other medications? Gingko helps to oxygenate the brain, among other things, but I don't know of it being used for depression. As far as I know, it's safe to take with the other things, I'm just wondering here why you're taking what you're taking and whether you've thought this out thoroughly with your psychiatrist or other professional. At any rate, it's very hard to say whether the B12 and the gingko or anything else for that matter is okay to take without knowing everything you're taking and why you're taking it.
I'm not sure what a "diplomatic" answer would consist of, but dully noted.
I personally am not well versed in the natural remedy department, but I know someone who is. I'm going to send him a PM and have him look at your thread.