Doctor suggests no sex, no travel, & taking progesterone

Hello, I am 25 years old currently 13 weeks 5 days pregnant with mono-di twins. This is my first pregnancy. All my ultrasounds and results so far show that my babies are growing normally. But today I went to see my doctor and she emphasized how risky pregnancy with twins are. She discouraged me from having any sex, told me I should not travel at all until I deliver my babies, and gave me "cyclogest progesterone" to take every night. Is anyone familiar with this medicine? My doctor says it is used to prevent miscarriage, but I have no history of miscarriages. Since it is my first pregnancy she says that she is not sure how my body with adapt to my twin pregnancy and therefore I should take all these precautions. Has anyone experienced this with their doctor? No sex and no traveling seems unnecessary to me since I've just entered my second trimester. Should I trust my doctor or get a second opinion? Any advice would be greatly appreciated!