You are probably an 'exempt individual' because you are here on a J visa- which is a temporary visa and therefore as you say you are considered a Non Resident Alien.
TurboTax doesn't support filing the 1040-NR. They partner with Sprintax. Contact them for more help
Also here are the IRS guidelines that cover your situation. Be sure to review the 'exempt individual' section
https://www.irs.gov/individuals/international-taxpayers/substantial-presence-test
