1. your profile is fine, and these school worth applying. my only suggestion is: apply more to place safe.
2. get a good GPA, and with advanced math/stat/econ course. (you have quite many already indeed....)
3. internship is not really that useful, unless the position is a really related one. (e.g. economics research assistant internship in central bank, but these type of internship are super difficult to get)
try your best to find a research assistant role instead.
Remarks for OP:
1. result are random for each single application, but the relization is just either 1 or 0. the only safety step you can do is: apply to more schools, and don't just apply to school that you expected to get, but add a couple more a bit lower one as safety.
Normally when talking about 定位, the best method is not talking about the probaiblity of a single school, but if a list a school is safe enough or not.
2. the reason why not NYU is seldom stated explicitly here, but as far as I read in quite some english forum, they are: relativly easy core course, and adjunt professor from industry instead of academics for teaching.
3. keep away from 中介 is the very first rule.