I can't really add anything that hasn't been said already but as Alec is 15 later this year I know just what you are going through and of course he will be missing his father and trying to come to terms with the circumstances. He sounds about right for a 15 year old to me and I agree that no medical help is likely to be needed at present. There will be days when he will shout at you, far outweighed by the days when you'll do the shouting but if you make your feelings clear and explain why you want certain things done(not when in mid- shout!) you'll stand a better chance of his playing by (most of)the rules. You all have to live together and he deserves to have his views heard as well.
As to pizza teenage boys have hollow legs! But as I have pointed out to Alec MANY times he may be a bottomless pit but my purse isn't so when a healthy appetite starts looking like pure greed I put my foot down-until the next time!!
Like others have said feel free to pm me anytime but I think you'll be fine!
Jane