What are the symptoms of low blood sugar?

Before I go on, I have a OB appointment next week so I will ask my doctor then sense I don’t feel like it’s something urgent I didn’t feel the need to rush into my OB’s office. But I would love to know other mommies experience. This is my 4th pregnancy (mommy to angel twin girls, a loving healthy toddler, and a angel baby boy). With my previous pregnancies I’ve never felt the way I do with this one. I’m only 12 weeks and I’m always tired, more lately. But I don’t feel like it’s tired like the normal pregnancy tired, more like a tired exhausted, faint, week feeling. I was thinking it could be low blood sugar but I’ve tried eating or drinking and still does not go away. has anyone else experienced this?