I had a bit to spare as well and I lost 7kg in the first trimester and then a bit more afterwards in my first pregnancy. DD1 was 4.04kg or 8lbs 14oz. She came at 42 + 3 weeks, so I don't think that you need to worry about the weight loss. Sometimes our metabolisms speed up during pregnancy and that is good for us to keep healthy and cope with the last weeks of pregnancy when we get big and uncomfortable. Eat healthy and good quantities and no matter of weight loss you are going well!