SS, my SIL's twins (born 19 years ago!) were boy-girl, and they were both over 7 lbs and went to nearly full term. I don't think they were considered premature by any criterium. Looks like your babies are on the same healthy path!
WPP, be prepared - your due date can never be much more than a guess because every baby's gestation time is individual to that baby. The due date is determined by the average human gestation time, the date of your LMP, and us measurements of growth. But, it is still an educated guess, nothing more. Where your baby's gestation time falls in the normal curve for gestation might never be known if you need to be induced or have a c-section for some reason. Just don't want you to get super excited about knowing THE date because your guess is just as likely to be right as whatever date you get after your appointment.