I'm in the subtropics so bananas grow here, lots of different fruits, rice is pretty cheap, it's more common than potato in our food. Potatoes just have to travel I guess.
I'm surprised you haven't gotten scurvy or something. I had restrictive eating disorder when young but it wasn't like this with the pickiness, more like I still enjoyed the taste of things but sort of wanted to chew them & spit them out because calories. I just didn't want to eat but still could enjoy when I did, until I felt like I had done something wrong, if that makes sense. If it was a small serving I could without fear.
Recovered for decades and I really enjoy flavors and textures, still can't really overeat without anxiety but certainly can eat well and feel ok about it. Few things I don't like - ham, raw tomatoes, sweet vegetables like squash, bland cheeses.
Did you like the cake? Do you think you might like a sweet bread, if you like bread? I do wish you could afford butter, that makes a lot of things better. Also do you want to enjoy more foods or no?
