Perhaps this is not the best time for you to fast? Sounds like you have a lot going on and fasting might be easier/more effective at another time. No need to stress about it — you can always do it when life is better aligned.
Some days are tougher than others. I wouldn’t read too much into it. Sleep probably does play into it. I’ve had days like that and woken up the next day and just sailed through it. Be kind to yourself and listen to your body. I noticed way more hungry days in the beginning so just know that it gets easier with time and the only prerequisite is to begin again each day.