@_marc97 Don't be! I know it's a mindfuck, but you probably do need to eat more to see results at this point.
I did the same thing earlier this year—I was sticking to 1450 calories, which was my sedentary deficit, without taking into account that I had started doing 75Hard and working out twice a day. And I wondered why I was exhausted all the time
Turns out, my maintenance at that level of activity and my weight at the time was more like 2500 calories. Life got SO MUCH BETTER once I started eating more, and I started being able to do way more in my workouts.
Play around on tdeecalculator.net. If you're walking 5 miles a day on top of lifting 3x a week, I would put that at at LEAST moderate exercise, meaning your maintenance is probably more like 1800. And 300 calories is huge, like another small meal or big snack per day!