Usually surgeons will provide a letter describing you had surgery and thus look different.
Having a boy photo and then appearing feminine can be a problem and leads to questions no matter if you had FFS or not. It may help then to bring a letter of your psychiatrist or if you already have it, legal documentation of the applications for name change process.
I would not do a photo right after FFS for a passport. It takes a few months for the FFS to settle, swelling to go down, so it makes sense to do that photo at least 3 months after the FFS, better 6-9 months.