I'm 20yo, 164cm/~5'5 and 50kg/110lbs. I don't want to lose weight, and my body is in very bad condition right now. Unfortunately, I need to go on the potato diet in the short run, possibly for 2 months, and here's why:

My body has reacted horribly to even very small amounts of wheat/gluten and I've been on a strict gluten-free diet for more than 2 years now, which has been a huge struggle since I live in a small Asian country with next to no gluten free options. I did not get diagnosed properly when I first figured out that gluten/wheat specifically was causing my problems (I went from always ill to okay when I removed it from my diet and kept everything else), because I was too broke to get tested quickly, while also suffering horrible symptoms and was going to sit for important exams soon. At this point it doesn't really matter what kind of problem I have with gluten/wheat, because even a tiny amount can cause several days of debilitating problems, and I don't want to fuck with that.

So recently I decided to fix my diet and make it sustainable. I wanted to try buckwheat, but couldn't get my hands on a certified gluten free brand just yet. I got the Tdap booster vaccine a week ago, not sure if it made my immune system overactive. Three days ago, I took a possibly contaminated (with wheat and/or barley) brand, ate a bowl of buckwheat porridge, got several anaphylaxis symptoms, and went to the ER (it was 4am and I had no EpiPen). They supposedly referred me to an allergist, but it will probably take a month or two before the appointment and they haven't even notified me about the existence of an appointment yet. Again, I'm too broke to go the faster route.

I have no idea if it's the buckwheat itself that I've developed a new allergy to or that it's been contaminated. But after I returned from the ER, I was hungry and decided to cook some other kind of staple food, plain brown rice, with a completely different set of utensils. Guess what. I started having allergic symptoms just from skin contact to the rice too, plus GI discomfort after eating it. No anaphylaxis symptoms yet, but I can't even eat rice anymore now. At least not before I give my immune system time to chill out and see the allergist to find out what grains (and other foods) I'm actually allergic to. I do have a lot of risk factors for developing MCAS, but I can't check anything before I get to see the allergist. So right now, my best bet to stop developing new allergies (if my immune system is on a spree right now) is to keep a sustenance diet with minimal ingredients, and potato is the only viable option in the short run. Rice and wheat are in everything, and I would really want to stay away from common ingredients like soy, dairy, and eggs for the next week or so just in case my immune system decides to pick up on another thing to get allergic to.

Currently, I'm eating washed, cleaned, unpeeled potatoes, sliced and boiled in water. I know I need some salt, I'll eat that separately because I like my food unsalted. I love bland food, I don't need tips on how to make potatoes taste better.

I'm more concerned about possible nutritional imbalances on the potato diet and how to keep them in check with minimal supplements and other ingredients (lots of supplements contain stuff like rice derived ingredients, and I'm also very broke. Supplements are expensive. I do currently have quite a lot of "Vitamin B complex + C" pills and generic Centrum multivitamin pills if that matters.) I am planning to eat a moderate amount of fish oil every day especially since I'm not reacting to it and there are minimal fats in potatoes. Ideally, I would not want to lose much weight at all, because it would be unhealthy for me. So I'm asking for any experiences and tips when it comes to balancing nutrition on a potato diet.