You were already stressing your body with OMAD for a week maybe it was a bit much for the beginning.
The 3 espressos are also a potential source of problems, it depends a lot how well you can handle caffeine for me its no issue but I used it targeted as little booster and done need to drink coffee like most people who drink coffee.
Potassium is important but usually unless the OMAD already depleted your potassium storage you shouldnt havea problem with potassium at 48’s/72’s. I can go dry or wet with no Snake Juice for 48s and 72s without a problem.
Light headache is normal in the beginning but also can be a result from too little electrolytes and too little water and of course from detoxing.
the tiredness and sleepiness the same but I woudl attribute that to your body already running on low due to possibly suboptimal OMAD for a week especially if you dont have a potassium source.