ya all your contributions will not go waste. meaning if you were working on opt, and h1 and later got gc and citizenship, they are all under the same social security number and the change of status does not matter if you have been paying for them. But don't be so hopeful because there are many rumors about ss getting bankrupt. Also if you plan on retiring in Nepal you need a long term visa from Nepal. New Nepali constitution talks about continuation of citizenship but no body is giving a flying fk to make any laws following the constitution.