What’s going on with me?

I’m almost 35 weeks and I’ve noticed recently (like the last couple weeks or so) after I eat or drink something sugary (sugary cereal and apple juice or a tiny can of mt dew with my lunch) I feel really...blah. It’s hard to describe but I just feel off, like kinda weak, tired, just overall I feel weird and maybe even slightly light headed? I’m not sure if it’s my blood pressure, blood sugars or what could be going on. It usually happens in the mornings after breakfast, and my appointments are at 9 am but of course it never happens on appointment days and the doctor says my vitals always look fine...but I wonder if somethings not fine 😕