I was studying abroad myself last semester and no one I know of had their universities/whatever organize travel etc. for them, so I think this is more common than some organization taking care of anything.

Reading from this:

http://www.exteriores.gob.es/Consula...dent-Visa.aspx

it says a permit to return to America is needed, not that a return ticket is needed. Might want to contact an embassy for confirmation, a print of an email could be helpfull in immigration if they really wanted to make it a problem.

But as the rule you mention is 1 year from the day you buy the ticket, even waiting isn't going to help as the return date is more than 1 year after the depature.
I'd personally consider the option of buying 2 return tickets instead (1 now and 1 later), if the prices are similar with one ways and return tickets, you can have the option for an almost free trip home for Christmas. In any case buying a flexible ticket, won't that cost almost as much as 2 return flights anyway?