Petguard Organic Cat Food substitute? Cat with lots of food allergies.need some help?

So Petguard cannot keep up with the demand for its Organic Mature Dry Cat Food, which after many food trials, is the only dry food my cat seems to be able to eat without vomiting. I’m down to about a three week supply and have yet to be able to find anyone, including Petguard, that has food in stock. So, if you had a cat that was allergic to WHEAT, CORN, SOY, YEAST, BEEF, VENISON, DUCK, LACTOSE, PORK, and LAMB what would you feed it? I’m hoping someone else is in a similar situation and could recommend a different food so at least I have a starting point.

Safe foods are:
Chicken
Oats
Barley
Flax Meal
Brown Rice
Carrots
Spinach
Potato
Peas
Quinoa
Kelp
Apple
Fish Oil in the food is OK but not a food with fish as a main protein…

Yes, the cat has seen a vet. No, there is nothing physically wrong with the cat causing it to vomit. Other than a sensitive digestive tract, the cat is healthy. Yes, the vet agrees the cat has food allergies. No, I did not do formal allergy testing as it is not in my budget, hence lots of food trials. Please do not tell me to take my cat to the vet; there is nothing she can do except give meds to try to soothe the cat’s digestive tract when she gets into a vomiting pattern. The cat has been vomit-free, other than the rare hairball, for over five years; I’m dreading having to switch foods and start the cycle all over again.

Any help is greatly appreciated. I’m including links to the food I’m currently feeding and the only other one I can find that meets the criteria…if you’ve had good or bad experiences with the new food I’d love to hear it. And if you know of anything else that might work, please, please, please, let me know!

Thanks!!!

Petguard Organic Mature: http://www.petfooddirect.com/store/product_detail.asp?pf_id=30175304&dept_id=1160&brand_id=304&Page=&mscssid=T2GF5VWJWGD88J6KKQ8UHH5T70S197K2

Natural Balance Green Pea & Chicken: http://www.petfooddirect.com/store/product_detail.asp?pf_id=301119712&dept_id=1159&brand_id=389&Page=&mscssid=T2GF5VWJWGD88J6KKQ8UHH5T70S197K2