Who else could have aided Gondor?

[gorthaur_cruel]

Boromir never said "Gondor". His exact words were

But still we fight on, holding all the west shores of Anduin; and those who shelter behind us give us praise, if ever they hear our name: much praise but little help. Only from Rohan now will any men ride to us when we call.

I believe by "us", he doesn't mean Gondor, but rather the fighting force of Minas Tirith. He also mentions "much praise but little help". Little help can be taken to mean "no help", or not a lot of help. We find out later that Lossarnach, Ringlo Vale, Morthond, Anfalas, Lamedon, Ethir, Pinnaeth Gelin, and Dol Amroth come to Gondor's help, but their forces were "always too few, always less than hope looked for or need asked". Thus, I think he's referring to those "Outlands" of Gondor. He does say "those who shelter behind us", and if Boromir's talking about the fighting force of Minas Tirith, that makes perfect sense.