To understand JRA, I found this .gov link that might help.
Since JRA is so difficult to understand, a good doctor is very important. If you would like to look at natural healing as an alternate or complement to conventional treatment, you could try natural foods. I have no idea if natural foods would help your condition, but you might want to explore it more. Eating natural foods means avoiding all processed foods like cakes, ice cream, soda, donuts, candies, pastries, crackers, cookies, and chips etc.
You could also look at herbs. I started with some very mild ginseng herbs that I bought packaged in tea bags - just one cup of tea a day - usually in the evening. If those herbs helped, then you could review other herbal teas too.
Also with your diet, see if you might be allergic to certain foods. You could also have strong reactions to some household products or environmental toxins. With some safe experimentation (by eliminating the use of some household products, for example) you might find some good results. Basically, what I'm saying is look at the natural side of things, to give your body the best opportunity to get better.
Check this out with your Mom and see what she says. I don't believe that it would be harmful to try eating more healthy foods. Have you been doing that already?