Confused about possible GD

Kaydee
My mom and grandma both have diabetes (diet controlled) and mom had GD with all 3 of her pregnancies. I have had lots of problems with low blood sugar and pretty much just eat whatever I want. I hardly ever drink soda and never have coffee, only water and tea. I am not over weight and have only lost weight since being pregnant. 
I failed the 1 hour test (I don't know my number) after 14 hours of (accidental) fasting. My OB ordered my 3 hour test yesterday, so I haven't taken it yet. But I feel like I will fail the 3 hour as well. So if I have it, how should I approach the topic of low blood sugar and trying to gain weight for baby on a GD diet?