Congratulations!
I know exactly how you feel. In fact I have started a few threads myself.
My twins are 11 weeks now. You will adapt, honestly. You’re stronger than you know. It is also a lot easier being a twin mum the second time around in my opinion as I think I would have struggled if I didn’t already have experience.
No, it is not how I planned it. I had a c section and I bottle feed. But you know what? It’s just as special. Personally I do prefer a routine, but it’s a relaxed routine of sleep/ feed/ awake/ nappy etc. and it’s adaptable.
C section was fab, one of the best moments of my life was the hours in recovery with my babies. I had my own music and lavender oils. I could have had a natural birth but didn’t want any risk and I’m happy with the decision. Recovery was hard for a week then fine after. I have fraternal twins and had my section at exactly 37 weeks (my hospital don’t let you go past 38). No nicu time needed.
I EBF for 5 days, then for various reasons mix fed for 6. Then moved on to formula. I was very anti formula before but with twins you need to relax and take the easier option which for me this was. I am naturally an attachment parent, I still am but in a routine based way. 
It hasn’t affected bonding, you can still hold them close, get lots of eye contact. It’s lovely. Plus DH shares the nights with me- I couldn’t do it otherwise. I do find with bottles they self settle a lot easier as we use dummies.
I am starting to get out more now. I have one colicky twin that loves the sling, and then my girl loves the pram. I highly recommend a mountain buggy duo with the cocoon! Oh and a twins feeding pillow- whether you BF or do formula.
Yes sometimes they are both crying at the same time, but I am far more relaxed. You will find strength that you didn’t know you had. Twin Mums are amazing!
It isn’t an easy pregnancy so do make sure you look after yourself. I could barely walk towards the end! It’s hard but so worth it. It’s okay to feel overwhelmed too, but you will be fine once it all sinks in! 