Given the fairly small difference between breastfed and formula fed babies in countries with access to clean water I often wonder why mums put themselves through so much in order, to the detriment of themselves, to continue breastfeeding?
My 1st was ff from the off, she was premature, badly jaundiced and super sleepy. We were on a strict feeding plan and she still took a very long time to gain weight.
My 2nd had formula in the delivery room due to gestational diabetes. She downed 30ml 30 minutes after birth and that made my mind up pretty swiftly to not be massively fussed. I tried, she wasn't interested.
Don't kill yourself over something that, in the long run, is pretty inconsequential in terms of the bigger picture of development.
Anecdotally, my 1st DD has one of the best immune systems of her peers (from nct/friends with similar age kids/school) and has a stomach of steel (she avoided norovirus even when her dad and I were down).
Formula isn't poison. If breastfeeding is causing YOU harm. Mental or physical then stop. There's nothing to be guilty about given a bottle.
And formula feeding isn't faffy. Get your partner to wash bottles. Get bottles you can sterilize in the microwave. Get a perfect prep. Use ready made formula. Piece of piss in comparison to my (limited) experience of breastfeeding.