Agree this seems too short - are you checking in any bags? Boarding usually closes at least 30 min before departure, leaving you with ca. 1 hour (assuming your USH flight is on time) to retrieve bags, walk to the international departures terminal (around 300 metres), check-in, clear security and immigration and walk to the gate. There is a "Fast Pass" queue for security (not sure if you're eligible, otherwise you can pre-book online for 20 USD) but no priority access for passport control.

As for the AEP-EZE transfer, this is also very tight but doable depending on traffic. I would normally allow at least 4 hours for this transfer.