I lived in Kuala Lumpur in 1979 during the refugee crises there and really enjoyed Malaysians.
The question on whether you can speak Malay or Mandarin wasn't yours, it was the result of the decision your parents made to send you to the US for education. Many Chinese Malay families sent their children to the US, Canada or Australia once it became clear that the political situation in Malay was becoming uncertain for Malays of Chinese descent. That uncertainty is the result of reasonable concerns that ethnic Malays have that they would become a minority as a result of aggressive immigration policies by the British. The Malay reaction is understandable but the inequality of the British Colonial history fell to the shoulders of people like your parents.
I would venture that people in the "Asian" community don't really hold it against you as much as you miss that part of your history.
It is interesting to note that a lot of Mexican American parents who arrived in the 50's and 60's forbid any Spanish to be spoken in their household and there are many second generation Mexican Americans in their 40's who have had to go back to school to learn Spanish because they want to help their children learn Spanish.
I wouldn't put too much weight on what other people think you should or shouldn't do, the real question is what do you want to do. If you want to learn Mandarin (or Malay) it has never been easier with great Community College courses and good on line assistance.
In the meantime when you get homesick make some great Satay and Gado Gado.
http://www.jamieoliver.com/recipes/vegetables-recipes/gorgeous-gado-gado/