Four months is common with eating issues but four years is torture. I would be seeking out help for that from clinic to clinic until I found something satisfactory other than the standard permanent feeding tube recommendations, easy for them but not for you.
In the meantime I can only suggest keeping a list of what can be swallowed easily and stick to those foods. Not having taste makes food boring but I am wondering if you also lack the sense of smell and or loss of touch in the mouth or back of tongue?