Hello A.,
Congratulations on your pregnancy!
Please take what I'm about to say to you, that I understand how you feel, It's an honest answer, and only saying it with love.
Not sure exactly what kind of response you are looking for, but from what I read, it seems like you are excited about this pregnancy, especially after your miscarriage. Your OB is most likely taking precautions so that you won't loose this one either. Not lifting more than 5 lbs. of weight, no swimming, unpolished nails, and stretch marks is a small price to pay for a childs security for it's life.
Lifting more than 5 lbs. will strain your abdominal muscles, puts pressure on your abdomen which may cause detachment of baby from uterus. Swimming also uses abdominal muscles to move around water. Nail polish fumes, if inhaled too much too long can get into your blood stream and cross over to your baby, 'cause everything you eat drink, and inhale will affect your baby, and when you breast feed, anything you eat crosses over to your milk. I ate buttered popcorn and then breast fed my son, he passed pop-corn smelling gas!
I was seven months pregnant with my daughter when I was 18 and I was put on bed rest for 2 1/2 months, just laying in bed doing nothing but watch tv, can't even walk outside. It drove me nuts. It was worth it, just to keep her from coming out early, so that her lungs will develop more in order to survive on her own.
Concentrate on your baby, you won't be on these restrictions for long, Worry about getting back in shape when your doc says it's ok to do so. understand the reason why your doc wants you in such strict restrictions.
Keep yourself busy, you have plenty to prepare for, keep educating yourself on babies growth, if you attend church, there are churches that offer parenting classes.
It sounds like this is your first baby, and between the age of 18-25.......Just having those 2 factors together means that you should'nt have any problems loosing the weight after having the baby.
Eight years after I had my daughter, I had my son at 27, At 18 I was 105 lbs. at 27 I was at 115 lbs. now at 30 I am at 113 lbs., So don't worry, you'll get your body back, you will have the baby to keep you busy, and if your're determined enough and still have some energy, you can work it all out.
I hope this helps,
Your in my prayers,
God Bless,
K.