I think a lot of posters have advised to try to stop worrying about your son's eating habits. I hope you don't take offence but I couldn't help but notice a few things you had posted and felt concerned. You mention in one post that DS won't feed himself but he's been told "As of February you will.....?" How can a 3 year old have any concept of what this means, even a bright 3 year old, and what does it mean?
In another post you say what your DS has eaten and it doesn't sound too bad, but then he refuses 2 meals at tea time and you say (and forgive me if I have this wrong) that he was sent to bed at 6.00 pm and in tears (was that you or your LO? I honestly think it is unacceptable to send a child to bed because he won't eat. Negative re-inforcement isn't going to work. You say you asked him why he doesn't eat and he said he "didn't know" - well of course he doesn't know, why would he - he's 3! Many adults can't explain their behavioural quirks let alone a 3 year old. Children are concrete thinkers and can't possibly understand this kind of question.
The other thing was you said "DS is fortunate in the amount of love he is given" (or words to that effect) but he isn't fortunate is he.....he's getting what all children deserve, the love and care of good parents. You are the fortunate ones to have 2 healthy children.
Look I'm sorry as I know this sounds very critical but your DS sounds SO much like my DGS - he is 10 and has been a fussy eater since he was 14 months old. He wouldn't feed himself till he was about 7 and even then he messed about (still does). The thing is he's not interested in food - at all - (unless it's sweet stuff) and messes about, taking ages to eat anything even now, and will use all sorts of distractions, fiddling with something/anything on the table etc.
I really hope you can relax and just not get so worried about your DS and I apologise in advance if my post is overly critical.