Gestational diabetes! Plz help

Hi there can anyone offer me some advice on the GTT test ? My consultant called to say that my level was over 7 . Whats a normal level in pregnancy ? I have to go to hospital next week for the test and im really worried i have it ? This is my second pregnancy and my first bby weighed 9lb9oz and i gained 6 stone . I only weighed 6 and a half stone before i was pregnant 
 This time round ive already gained 3 stone and im 30 weeks.  Could i have had gestational diabetes first time round and it was missed ? 
Please share your stories and views as im so concerned xx