I have $190 of OBC ($100 is from the share holder credit and the other $90 was given by my TA and don't want to use it towards any of the above things. I kind of regret buying FAS because I don't really drink all that much and the $100 would have paid for that for me (I didn't expect to get the share holder credit as I booked a week before the sailing and because I'm a party of 1 who didn't pay a single supplement...not in a studio cabin).
I figure to use it for shopping on board. W
You can cancel some or all of the FAS before sailing as long as you do it more than 3 days in advance. If you don't drink much or don't want the specialty dining, just call your TA and have it removed. You said you booked a week before the sailing -- do you still have at least 3 days left or are you already within that window?
If you can't cancel FAS or if you still have OBC to spend, you could:
Pay for on-board activities, like an escape room, Canvas by U painting class, or the go cart