First of all, I am so sorry for your loss. It is ok to grieve. And there is nothing wrong for you for thinking about an alternative universe... the one in which your 20 year old is getting ready to come home from college, or whatever images you have in your mind. And feel sadness for the reality that never was. Go ahead and feel that sadness. But don't feel the guilt about the sadness. It is ok.
Then, look at your beautiful son. This is not a fantasy, alternative universe. This is reality. This is the son, who, 20 years from now, will be the one coming home from college... or whatever he does. Create the family traditions that he will cherish. Live inside of the fantasy. Allow yourself to feel the joy. And I really believe that if you let yourself feel the pain, without guilt, then you will also be able to feel the joy. Both emotions are real, and can exist back to back.
If you find that you really cannot feel the joy that you know that you deserve to feel, then reach out again. A lot of parents feel depression after an adoption, and are too ashamed to seek help. There is no shame in feeling a real emotion. But if you believe that that emotion will overtake you, or that it will interfere with raising your son the way you want to raise him, reach out, and get help.
I send you big hugs, and hopes of much joy in the weeks and months and years to come.
