I don't have twins, so I really have no idea what you're going through but let me tell you that they are still so little. My boy is 8 months old and sleeps through very rarely. He is often up twice a night for a feed and will only sleep for 30-45 minutes at a time during the day.
It really hit me at 6 months, so many people told me that he would sleep through by then but he isn't, and many of my friends with babies are in the same boat.
I was really struggling to settle him, so we went to sleep group two days ago and I know feel much better having some tips on how to prepare DS for sleep and to help him settle. Perhaps see your MACH nurse and talk to them?
Good luck, I hope you do get some more sleep soon.