I went back to work when DS1 was 8 months. It was over 5 years ago now so my memory isn't great but i do remember i began sending some formula for those few feeds he'd be missing from me (in a bottle). He'd barely had a bottle before that but as they do, they tend to take it from others if they're hungry enough when mum's not around. I think my hours were 8:15-4:15 so we'd feed first thing in the morning, i'd pack enough for 2 bottles while i was at work, i'd collect him by 4:30 and feed him the moment we walked in the door. He was fine with this and my boobs were quite ok with it too. Probably felt it in the first few days but nothing too uncomfortable from memory. I only worked 2 days so all the other days were 'normal' and we kept this going until he was 13 months old when we weaned.

DS2 was 10mths when i returned to work again same hours 2 days a week and he really wans't a bottle fan. I think if anything i tried formula in a cup but at that age wasn't too fussed and tried to ensure that he had other dairy options for those days until i fed him when we got home. He weaned day feeds at 14 months. Thinking that your DD and my DS2 are similarish i'd offer a cup and not a bottle and send the dairy alternatives if you can, if she's hungry she'll eat, she'll adjust.

I suppose all you can do is see how it goes with your milk and hope that you don't get too uncomfortable, if you do you'll have to figure out a manageable way to get your supply to adjust.

Be assured that your child and your body will adjust and hopefully both will be happy to continue on your new schedule to breastfeed for as long as you both choose.