I had a similar story. My cat ate very little, I gave her dry food and wet food - but she hardly ate it. Then I tried to feed her natural food, meat, sausages or fish - she didn't eat at all. She was also very thin at two and a half years old - weighing almost 9 pounds if not less... Eventually the vet diagnosed kidney disease - that was the cause. So it doesn't always depend on a picky nature! Now she eats regular fodder and sometimes I give her meat and catnip. Btw, not all plants are healthy - see here. Now I'm keeping a closer eye on what plants she tries to eat while I walk her.