Even before I was on metformin (even as a teenager) I've felt and always feel that way on Atkins, and other low-carb plans during the very low-carb phases of the plan. I thought it was the "induction flu" that everyone talks about with low-carb diets. It never went away (as Atkins and other plans promises that it will). To me, it was proof that low-carb plans were unhealthy and dangerous, especially since I actually passed out a few times on Atkins.
What I didn't know was that for me "the induction flu" was a combination of too few calories and low blood sugar (or a rapid drop in blood sugar). If I had eaten when I started feeling that way (especially something with some fat and a bit of carbs in it, like a tablespoon of peanut butter), the feelings would have passed.
When I was prescribed metformin, my susceptibility to those symptoms got much worse. I also was able to test my blood sugar, so I found out that the feelings were a result of either low-blood sugar or a rapid drop in blood sugar.
On very low-carb, I don't get "hunger" in the way I ordinarily think of it. My husband notices that I should eat, before I do (I get extremely irritable, then I get a pounding headache, then I start feeling dizzy and nauseous and if I still don't eat, I'll even cold-sweats and then be at risk for passing out or dry heaves).
I now recognize the symptoms as low-blood sugar or a sudden drop in blood sugar. It's why I can't eat sweet foods like donuts or pancakes for breakfast (I was never able to, even as a small child, without getting sick to my stomach about an hour or two after eating something sweet on an empty stomach).
Eating more frequently or eating something with a bit of fat and carbs at the first sign of yucky feelings (like a tablespoon of peanut butter).
It also helped to always eat protein or fat with carbs. Since I've been on metformin, I can't even eat fruit on an entirely empty stomach. So if I want fruit or other carb-only foods for breakfast, I have to add some protein and fat. A dab of peanut butter, a cup of yogurt, or a piece of cheese - something with some protein and/or fat.
I even have to be careful with "good carb" high carb foods like sweet potatoes and whole grains. Most grains and breakfast cereals (even with skim milk) are likely to trigger problems without more protein added. Only oatmeal seems to be the exception.
I'd recommend trying experimenting along with journaling to help you find pattenrs, not just documenting what you eat, but when you eat, and how you feel. Experiment with one change at a time, and be consistent for at least 2-3 weeks.
For example, eating smaller, more frequent meals.
Or eating something as soon as you start to feel that way (you can experiment with different kinds of foods protein, fat, carbs or a combination of).
Try not to jump to conclusions. You can't be sure that what looks like a pattern isn't actually coincidence or due to something else, so you have to re-experiment a lot (and pay attention to what else is going on - like your monthly cycle...).