I LOVE Bug's answer, You are pregnant, NOT handicapped.
I honestly was going to be one of the first to answer, but thought I better not.
I don't know how old you are, but I was 32 when I was pregnant with #2. I had an almost 4 year old boy getting him in and out of the car seat. I was working 12 hours shifts as a floor nurse. And had carpel tunnel problems as wells as sciatica problems. I had horrible pelvic pain and they kept watching me for pre-eclampsia and I wouldn't have thought of going into the system! Hell, I fell and broke my elbow when my baby was just 3 months old and the doctor wouldn't cast it because where the break was located. But cautioned me that if I injured it again I would require surgery. I had a 3 month old AND a 4 year old and that never occurred to me.
Updated: Mj, do I think you need/deserve a handicapped sticker because you are pregnant with a 3 year old, no! But for me, as an RN, the fibromyalgia would make me think twice. I know and realize that is as debilitating as a disease you can get. And now agree with some of the other posts that all you can do is ask your doctor and leave it up to them.
And as an RN who used to work for some lung specialists I also realize that not every 'handicap' can be seen as soon as people get out of the car.
As I said, I still stand by my original thought. Many woman have issues while pregnant and even with more little ones in tow. But, I will cut you a little slack with the fibro diagnosis. I wish you comfort in your last few weeks.