What size are your "three lenses?" I have a T1i with kit lens, 50mm lens, 50-200mm lens, two filters, filter adapters and I cannot fit all three lenses plus filters and adapters in the bag, at least not in a way where I can keep the lens attached. I could probably make it work if I took the lens off the body and stacked the 50mm and kit lens on one side, the 50-200mm lens, filters and adapters on the other side and the camera body in the middle (you can't have three lenses in a row in this bag), but there is definitely no room for battery charger, battery cover, cleaning kit, etc., if I do so.
Also, you must have a rather small flash. I definitely couldn't fit a flash in no matter what I did. I'm glad you're pleased with your bag, but you're making it sound much larger than it really is. :-(