If you don't have any external leaks there's few other places it can go bsides out the tailpipe. Just because you're not seeing major smoke doesnt mean it's not burning it. 1 - 2 quarts going past the rings in 3,000 miles will be difficult to detect.
I believe you're due for spark plugs at 45,000 mi anyway. When you have that done ask your mechanic to perform a leakdown test while he's there. Also keep track of which cylinders the old plugs came out of and note whether any cyl seem darker than others.
Keep in mind that all engines consume some oil during normal operation. Some more than others. But I would consider 2 full quarts in 3,000 mi slightly excessive.
Best of luck!
