Taxes & etc... It won't be much but at this point every penny helps.
I just got off the Silver line with a very pleasant agent who explained the only way I could wind up being charged additional fare is if they cancel the return ticket and re-issue it as a one-way. However they can't retroactively cancel a ticket that's already been partly used, and there is nothing further to issue.
I booked the redemption last night. I'm going to go ahead and cancel the return - let's hope she was right.
As to moving it to March instead, I thought of that but there are a couple of reasons why I don't want to. First and foremost this relocation is a strategic life move for me, and I want to give it every possible opportunity to succeed. Second, the fees and taxes on the redemption are not much different than the change fee would be, and if the refund comes through it may even work out to be less. (Plus it's a great excuse to fly F - I am an FTer after all

) Fortunately when I say "run out of money" I mean exhaust the budget I have set aside for this endeavour, not begging-in-the-streets broke.