Expectations are disappointments in the making. Sounds like you fell into that trap.
Instead of focusing in what you do not feel, focus on what you do feel.
You feel obligation. You don't want to feel obligation, but you do. Do you know what obligation is? Do you know how rare the emotion we call obligation is? Do you know how many people "like" their children and feel no obligation to them at all?
My goodness man, reconsider your perspective on all this. Obligation is love. Fulfilling your obligations, is the expression of the love you feel for your son. Your fear of rejection by your family reinforces your sense of obligation to your son, but do you know why? Answer - because you love your family.
Instead of fighting your sense of obligation, give into it. Dive deeper and deeper into obligation and let it fill you up. Deep inside obligation you will find the love you cannot feel when you are fighting it. You can't feel something you are fighting.
You think love inspires obligation. You have it backwards. Obligation inspires love.
People say they don't do anything because they feel so bad. If you want to feel good, you have to do something good. People feel good about the things they do. People feel bad about the things they do not do.
You act on your feelings of obligation. Let yourself feel good about it - please let yourself feel it.