I'm having the same problem. My freezer stash is down to just 7 ounces!!! I'm on an elimination diet similar to yours....no wheat, dairy, soy, eggs, fish, shellfish, peanuts, tree nuts, citrus, berries, chicken, beef, corn, oats, tomatoes. I've been on this since DS was 1 month old. (He's now 10 months) So, I've never been able to get more than 3 ounces combined when I pump, and it's usually just 1/2 to 1 ounce. Sooo frustrating!
I'm going to try the power pumping!