Can’t Sleep at 30 Weeks With Twins

by Petro.
(South Africa)

I’m a 24-year old, 30 weeks pregnant with mono-chorionic twin boys. It’s my first pregnancy, and I’m not always quite sure what is normal and what is not. No women in my family or on my husband’s side have ever had twins, and neither have any of our friends, so I don’t know who to ask.

When I complain to my doctor about how uncomfortable I am, she says that it is to be expected, but I need practical solutions, instead of the pregnancy magazine advice to "...make yourself as comfortable as possible."

For the last week or so I've had immense trouble sleeping, since I am no longer able to lie on my back, as it hampers my breathing, lying on my stomach is out of the question, for obvious reasons, and my hip-bones, or upper legs go numb when I lie on my side for a period of longer than, say an hour.

Throughout the pregnancy I've been sleeping on my side, but it seems I'm getting too heavy.
The pillow between the knees doesn't seem to make any difference either. I'm scared that this is a sign that I'm getting too heavy, and that the babies are preparing themselves for birth. They are both still growing at the rate of single babies, and my belly have lowered and expanded in size to such an extent that none of my maternity wear covers it any longer. I've also discovered a multitude of new stretch marks on my lower belly, which seem to have appeared over night.
What are the signs that the labor is eminent? I hope to carry these two for as long as possible, as every day of gestation is vital. Is my level of "uncomfortability" normal, and what can I do to alleviate pain? I've already stopped working. Bed rest won't be plausible as I experience pain, when trying to rest in bed. Anyone?