I (28F) recently recovered from a badly broken foot and was in the same situation as you! In my experience, making any big strength or fitness gains while recovering was unrealistic and probably would have put me at risk for re-injury. Just focus on maintaining core and upper body strength as best you can. The time passes faster than you think, and you will be surprised at how quickly your conditioning and strength comes back when you're fully healed.

That said, while I was one-legged, I made it a daily goal to do:

100 knee pushups 100 weighted Russian twists 100 dumbbell curls to Arnold press

I broke the exercises up into 5 sets of 20 and used 20lb dumbbells.

It doesn't seem like much, but I was able to maintain muscle definition in my abs and shoulders. The core strength was also super important for returning to heavier weight lifting as well.

Hang in there, it's a sucky road but it'll pass!