Is this normal?

Abigail
I'm 32 weeks pregnant now and have been diagnosed with gestational diabetes. 
From week 12 to week 28 I gained just over 6lbs. I got weighed at my 32 week appointment & have lost a lb, meaning that basically I've only gained just over 5lb my entire pregnancy. 
Is this normal? I'm not small, U.K. Size 18, but I'm concerned that I maybe should have put on more weight at this stage especially if they think my little girl could be larger than expected because of the GD. When I asked nobody really told me anything. Am I worrying over nothing?