The small splash of cream in your coffee is much less of a concern than the cereal. Cereal is pure processed starch and sugar, and will cause a blood sugar spike and an insulin spike to go with it.
Black coffee is totally OK during your fasting period. You don’t have to eliminate coffee or feel guilty about it. I’d focus on eliminating the cereal, and stop worrying about the coffee.
I wouldn’t even worry over-much about putting a small splash of cream into the coffee, as long as you don’t put sugar, and don’t use a lot of cream. Using a bit of cream in your coffee is technically a “dirty fast,” but it does very little damage.
But see if you can learn to drink it black! I’ve heard some people recommend a tiny pinch of salt — it doesn’t make it taste salty, but it reduces bitterness.
Edit: Here’s an article about adding salt to coffee with some recommended amounts! Apparently 0.5 g salt per 1 L of brewed coffee is recommended — not sure how that translates to what to put in one cup of coffee, but could do the math based on the volume of the mug…
Black coffee and a pinch of salt is a neat trick, caffeine and electrolytes for the day.
I wouldn’t worry about calorie reduction just yet, rather play with the timings of meals first to see what what you can live with. If you can slowly work your way to omad calorie counting is a non issue.