Hire an engineer to design it for you. If you move it up in the attic it is quite a bit more work.

What kind of house is this? You've labeled walls as "load". Are you indicating they are load bearing?

It’s a two story traditional. Built 1960. Yes - load = load bearing with a joist resting on it.

It's doubtful all 3 of those walls are load bearing. Which ones line up with walls underneath which will then line up with beams or walls in the basement.

Just because a joist runs across a wall doesn't mean the wall is load bearing. It could indicate that, but it is also possible that it's just a partition wall that happens to cross under a joist. The structure has to be evaluated as a whole.

You need an engineer I doubt very much these are all load bearing. There is no way to know without having it evaluated. And better to be done NOW

Any pics? The 2x12s are only where shown? A little confused

We ended up going with option 2. Running 2x10x12s across the section and scabbing them on to existing joists. I double-checked my design with 3 structural engineers and they’re all good with it.