To be rather blunt, it wasn’t smart for her to quit her job to be with you right before the interview and AOS. Maybe you two are very young, but that is not the move most people make when undertaking to sponsor an immigrant.
Have you guys looked into the cost of the AOS/ROC fees, which are set to have massive increases this year? US immigration is not cheap, and if you’ll be unemployed here for the better part of a year, you really need to think hard about affording it all. It will cost thousands of dollars.
While it’s true that London is not as hard-nosed about sponsorship as some consulates, the reality of poverty as a new resident in the US sucks.