Safe exercise during twin pregnancy
Congratulations on the twins. What fun!
As for your question..... Your physician recommended that you stop your step and kickboxing. I wonder how he would respond if you asked if you could attend a specialty prenatal class, providing that there is one available in your area.
I have had many women pregnant with twins in our prenatal fitness classes. Physician advice on exercise with twins varies with the physician and since I do not know your medical or obstetrical history I will have to advise you to go along with what your doctor has told you.
As for weight training.... I do not agree with your friend that upper body work with light weights will put added stress on your belly. You will need upper body strength when it comes time to lift those two babies, two carseats, a diaper bag for two babies and that double stroller! As for squats, they could be modified to plie squats. I would recommend to eliminate the lunges and just do the plie squats. Above all, listen to your body and adjust your workout accordingly. If it is the least bit uncomfortable, do not do it!
Again, your physician's recommendations were for a reason and I do not know if he had a specific reason in your case or that he just does not allow his "twin moms" to exercise. That is why above all, I will have to defer to the physician's recommendation.
Keep in touch. I would be interested in hearing what he says in the future.
Sheila