possible gestational diabetes but I haven't gained much weight?

I'm 32 weeks and I've only gained 8 lbs. I weigh 138 and I'm 5'6 in height. My belly looks so small still. I bought my own meter and have been testing myself and my numbers are low. I went in for the 3 hour glucose test and tested myself during it and my numbers were high. I'm still waiting to hear back my results from them.
Could it be that I have gestational diabetes but have been managing it well already ?
Edit: I know it can happen to anyone, but I thought My baby would be getting a bit large & I'd be measuring ahead, but she isn't. 

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