1) you should apply to a higher ranked program that is ALSO accredited.
2) just the fact that you made it to Nanyang Technological University is a monumental achievement. i know about the education system in singapore. going to uni in s'pore isn't like going to uni in the US.
3) take the GRE and let us know what you got so we can help you choose a good grad school. o, tell us the percentile!