OP, I was also desperate to get out of hospital after an EMCS with early twins. I allowed the maternity ward to give them formula becuase of all the fuss about feeding and ml intake.
What I didn't realise at the time was that their hidden agenda was to free up my bed asap, and if that meant getting my babies on formula so they could tick the feeding box and write down a number, then that's what they did.
So I expressed so they could get the colostrum, and continued to express and mix fed my twins. But I became more anti-formula over the weeks, I just didn't like the smell and figured the human body wil absolutely make better designed food for babies than a company using partially digested cow's milk. So I got my pumping schedule sorted, and tracked my amounts pumped, and slowly increased my supply so that after about 2 months, I was feeding both twins breast milk exclusively. I actually got up to 1.8 litres a day at peak. I pumped 4 hourly round the clock, though when really tired I'd give the 4 am a miss.
As the twins weaned I went down to 4 pumps a day, then 3, now at 14 months I pump just twice, so just enough for morning and nightime milk. I am gradually trying to get one to accept cow's milk, but at the moment she isn't playing.
But more importantly, the pumping regime has been HARD. Although I'm glad we did it, when I look back I can see that my biggest mistake was not getting my twins back on the breast, as they were when they were born, and letting the hospital give them formula, and creating nipple confusion. I so wish I had used resources and taken advice to relatch them; it would have saved me loads of effort.
At the time, I just thought it wouldn't be possible to relatch them, especially one of them, but now I see that it would have been, it may have been a stressful few days, but definitely preferable to expressing for over a year, by a long, long way.
Best of luck whatever you do, and congrats on your new baby girl.