Oh, please don't doubt yourself! People say stupid things.
My DD is a fussy eater and is fairly small... She's getting better, but there have been times I've worried that she's not eating enough and/or whether she might get sick etc. How wonderful it would be to have a child that likes food and eating!
I think you must be doing a wonderful job feeding him those lovely nutritious fresh foods. He is a lucky boy to have such a caring mother. Keep up the good work