Maybe too low of calories and too long of fast for a beginner. I think fasting is better to start without the calorie restriction to start and then inch is back after a few weeks once your body adjusts to the fasting schedule.
Honestly if this is your first time with IF i would start with 14-10 just so you get used to it then once you get the hang of it go to 16-8, i know my body didn’t like the sudden change of no food until 12 pm also if you don’t mind me asking what kind of foods are you eating during your eating window
Switch to 16:8 first for the first few months and climb your way up there.
Your body will need to adjust, doing higher hours from the start is a disaster waiting to happen.
Also dont focus yet with eating lesser calories, it will come. Eat as usual but with lesser portions and avoid any junk foods or processed food.