Tested negative for GD but fluid levels still high. Anyone else?

Sh

I failed my 1 hour and passed my 3 hour. So I don’t have gestational diabetes. Today my amniotic fluid was at 24.8, which is high. So the doctor told me to cut out carbs and sugar. I’m not a diabetic and I haven’t gained much weight. So could my fluid be rising bc of other problems? Anyone have experience with this? Currently 30+3. I have gained 12 pounds. I don’t snack all day or eat a ton of sweets, but I do snack every now and then.