I'm facing the same problem as you. The rash started around week 8 and it just spreads. I find the itch really unbearable at night when I'm trying to sleep and it kind of affected my sleep as well.
The doctor also said that it is caused by the hormones and there's nothing much he can do except give me some antihistamine. Sigh.....
I find that scratching makes it worse so I try not to.... and cold compress works. There was once I was desperate and got my husband to apply XO on my rashes, it helped to soothe it for a while.
BTW, this is my 2nd pregnancy and I didn't have this when I had my first either..