Pregnancy Pillow

So I am days away from being 16 wks and I suffer from pretty severe sciatica pain, by the time I lay down at night it hurts pretty bad. It only seems to be getting worse as I get further along, and my doctor told me flat out there was very little I could do to relieve the pain and that it will likely only continue to get worse. I'm thinking a good pillow will at least help a little.

I am having trouble deciding on what kind of pillow to buy and what brand. I'm an extremely light sleeper, have tons of trouble falling asleep and wake up a lot throughout the night. I like sleeping on my left side, and sometimes sleeping on my back (i know tsk tsk) would I be better off with a C shape or a U shape? I sleep on a full sized bed. Thanks!