Recently had gestational diabetes- confused!

I am after some advice if possible. I got diagnosed with gestational diabetes in my third trimester- my glucose tolerance test reading came back at 15. I was immediately put on insulin for the rest of the pregnancy. Since I had my baby girl 5 months ago, I have pretty much given up refined sugar. My glucose tolerance test at 6 weeks came back at 5, so I was told I don't have diabetes. My blood sugar seems to recover ok and is under 9 most of the time 2 hours after meals but every now and then, usually after a big carb meal, I get readings of 11 or 12 two hours after eating. I feel a bit confused as I have been told I don't have diabetes but I know it is not normal to still get high readings with things like porridge, potatoes, fish and chips. Any advice would be appreciated.