Well, itching like that certainly does sound like allergies. It also sounds a little as though you've been trying to treat the symptoms - but what you actually need to do is identify and eliminate the cause(s).
It is actually possible that the problem is something environmental, of course. Dogs have been known to be allergic to household cleaners, air fresheners as well as plants or grass. LOL - I even recall a member here whose dog turned out (through allergy testing) to be allergic to dog hair, though fortunately only mildly
Had you thought of having allergy testing done? It is relatively expensive, but at least should tell you exactly what the culprits are.
Since she's been chewing her feet constantly for a year (ie. this isn't a seasonal problem) it is quite likely that the problem is something to do with her food. I presume she is eating a full barf diet - a wide range of RMBs as well as fruits and vegetables... Do you have a "main" RMB, such as chicken? If so, that actually could be the cause, or more likely, the fat/skin. I realise she's been on a natural diet since she was a pup and hasn't had the allergy problem that long, but allergies are something that can develop over time.
Sooo. The options are really to either take her for allergy testing, or, if you think food is the most likely problem, then you could narrow down the problem foods by putting her on an elimination diet. Fortunately, elimination diets are easy when you feed raw, since there is no problem with feeding individual things
The way an elimination diet works is as follows:
First you choose a food to feed exclusively for a three or four weeks. An RMB source, I mean. But it should be something that the dog has
not eaten before, so won't have any pre-existing antibodies against. So this might be something like venison, or goat. Doesn't really matter what (though if she's eaten a lot of chicken or turkey in the past, I wouldn't personally choose any form of poultry). You feed this exclusively for a few weeks and see if her allergy problems clear up.
If it has no effect on her allergies, then food may not be the problem. You can try another "exotic" RMB just to be sure, but if that has no effect either, then it is fairly reasonable to conclude that it is not food allergies that are the problem, and she either has environmental allergies or a different problem altogether.
If the allergies *do* clear up, then that's great. You now know that it is food that is the problem. The next step is determining *which* foods are problematic. That is achieved by adding *one* new food item to her diet - something that she has eaten before, or that you want her to be able to eat. Feed her that for a week. If there are no reactions, note that one down as "safe". If there is a reaction, that's a food item she can't have and you should return to a "safe" food for a few days until any sign of allergy symptoms are gone. Then you add another new food item, feed it for a week, and see again about any reactions.
You continue this until you've got a pretty extensive list of OK foods and not-OK foods for her. That would include a range of RMBs, fruits, vegetables, eggs, oils - basically anything you want to be feeding her.
Good luck!