Weight lose

Manda
Hi, just looking for advice. 
Today I'm 13 weeks pregnant, I can't keep any fluids or food down. With multiple episodes of vomiting a day. In 7 weeks I've lost just over 1 stone. Doctors have told me not to worry but I feel my baby isn't getting what he/she needs. They won't do anything unless my urine sample comes back dehydrated. I'm on anti sickness medicine but I doesnt really do anything. 
Anyone in the same boat ?