What does your e-ticket receipt (not itinerary, but the e-ticket receipt issued by FI, say as to bag fees for your ticket. As this is a US departure, the US DOT post-purchase rule applies and it, among other things, requires that the e-ticket receipt specify the charge, if any, for the first and second bag, and also provides that those may not be increased once the sale is completed.

Start with the e-ticket receipt.