My current toilet is measuring at 11 inches even from the wall (not the molding) to the center of the bolts. Looking around I see a lot of people saying that they saw somewhere else that a 12 inch rough-in will fit, possibly with an offset flange, but I'd like a more authoritative answer if possible. My house was built in 1900, so a non-standard size wouldn't really shock me.
Yes. You could cut the floor around it and put the offset flange like Home Depot model #889-POMPK but it will probably get to more than 12".