On what basis is your application so weak that you can't get into a top 100 school? You have a great GPA, research experience and a published paper. As long as you attain excellent GRE scores and develop a strong SOP / writing sample, your chances of getting into a top 20 school are as good as anybody else's. Besides those general factors, no one can tell you exactly what your application has to look like in order to get in -- the circumstances of admission are more or less arbitrary.