I hate to say this, but I think you will just have to get under the car and track down the leak. We can sit here guessing all day. Something dumping a quart of oil every 3 days is going to be blatantly obvious when you spot it. If your engine bay is dirty, as I suspect it may be after leaking this much oil, you should probably clean it. That will help immensely in spotting this leak. Still need help? UV Dye + Black light. You look for the leak at night then, and the dye will light up the leak like a Christmas tree.
The only other place I can think of would be around the oil pump, which is integrated in the timing cover, but again, you tell us where you see the leak on the engine, most anybody here can tell you how to fix it usually.