I'm wondering if you are having an issue with oil bypass, as in going through the breather/PCV and ending up getting burned through the intake. A simple catch can would prove this out for you. This happens quite a bit and is easily solved. 

Two things. 

The leakdown test will not tell you anything about your oil loss. Its not what a leakdown test if for (check the link in the @DucatiKiller answer). 

Secondly, the oil has to be going somewhere. I'll guarantee you if it was leaking in the amount you're talking about, you'd see puddles and/or oil on the engine itself where its leaking. That's a significant amount of oil to be leaking or for the engine to be swallowing, for that matter. 

If you aren't noticing either puddles or smoke from the engine bay (not tail pipe), you aren't leaking it. Check the inside of the tail pipe(s) for oily soot. That may be an indication. It may be smoking from the tail pipe, but you may not notice it (people behind you while you are driving probably would though).