Hi,
i don't know much about how to answer your question about your bag of waters. But, I am experiencing preterm labor due to incompetent cervix. My cervix has been short almost the entire pregnancy and was with my first preg. Too. How short is your cervix? Did the doc. Tell you? That's pretty importatnt becasue if it is just a little shortened, you should just take some minor precautions, no sex, take it easy, maybe light duty at work. But, if it is really short, you need to be on strict bedrest. All doc.S opinions differ, but I am in a very conservative group and I have been on bedrest since 16 weeks. Your cevix should be about 3-4 cm. Anything below 3 is short, but not a huge concern unless below 2.5. This is known as effacement when your cervix is shortening, and it is a way of your body preparing for labor. The first group I went to told me that I would have to have 2 losses before they would diagnose and treat me for incompetent cervix, needless to say, I switched immediately b/c I wanted this baby, and didn't see the need to put myself and my family through 2 losses. You may want to speak more directly to your doc. And ge their stand on the issue and decided if you are comfortable with that. If your cervix continues to shorten, you should requestion steroid shots to develop the baby's lungs in case s/he is born prematurely as that is the biggest problem usually in preemies.
With sex, my Dr. Told me absolutely no penetration, but that he didn't mind orgasm and other forms of foreplay and sex. Hope that helps.
Sorry I wrote a saga, but this could be a serious issue for you and your baby. Taking precautions could help delay your delivery,if your cervix is real short.