huge hugs Nicola.
My job has gone from bad to worse over the years and even though (with lots of rescheduling, locking myself into cupboards and fights with my boss and HR manager) I was easily able to pump from when Ozzie was 4 to 10 ish months twice a day for 15 mins as I ate my lunch or had a cup of coffee, I still had no support, no understanding from colleagues who had also BFed etc etc. as they fed all night long or had given up before going back to work, or took 2 yrs off etc etc...
By the time I went back after Emma, I had no breaks to do this whatsoever, no time, loads more paperwork etc etc but as she was a little older, it was more doable (she was heading for 8 mths). She'd never taken to the bottle either. Still though, I knew I could do the am feed everyday, some kind of afternoon feed and bedtime and DF so she just ate solids and drank water all day long. But all day meant me feeding her 6.30am, back at home at 4.30pm, 5pm at the latest. These days it would be later...
If I had a LO now - in "this" climate of outstanding schools and wrecked teachers, well, I am sure I would be just like you and wondering about it all...but I wouldn't intro more formula just yet...things may all just fall into place when you're back. Some days she'll need more bottles, some less....
I would not change anything around for now. You're sick and not in a good place. So hard to go back midyear. And parent's evenings just after you go back? Blah!
Huge hugs xxx