Another Test!! Question

So I’m 28 weeks and 5 days today. I went in for a scheduled ultrasound because I was diagnosed with a low lying placenta (1.75) at 19 weeks 5 days. My baby was also breech. So I’m lying on the table, the Dr starts the ultrasound. She says,” Oh she’s head down and your placenta has moved all the way up (8.32) Great news!! Then she says,” But her head.” She starts to measure her head. I’m laying there watching as the numbers go up and up. In my head I’m like damn. My doctor said she has a big head. Her words not mine. But I agreed. She finished all the baby’s measurements and told me my baby is measuring almost 4 pounds. The size of a 33 week old. So she is measuring about 3 1/2 to 4 weeks ahead. She asked me how I was feeling. I told her I was feeling fine, minus my sore hips. Then she said that she wanted me to come in tomorrow morning for another glucose test. I passed the first one by the way, 10 weeks ago. I’m sort of bummed and kind of nervous for the results. She said it doesn’t seem like I have it but better safe then sorry. Since I seem to be carrying large. I agreed.

My question is:

Could I have Gestational Diabetes, without having any symptoms other then a baby on the larger side?