fasting?

Odd question about fasting for Good Friday.

I am underweight, plagued by food allergies, and typically only get <1200 calories a day in two meals. Tomorrow, I will likely only have time to eat 2 meals between church responsibilities (I’ll be there from 12pm to 4:30, and again from about 5:30 to 8:30 if I have the strength, God willing!!).

Fasting mandates one full meal, and two smaller ones that don’t equal a full meal. But, if I ate two 500 calorie meals, is that legitimate fasting for someone in my condition? Or should I split it into three smaller meals to more closely match the default criteria? I don’t want to “bend/ break the rules”, make excuses or get "special treatment’; I’m just in a medical diet dilemma and figured I’d ask for input. I want to fast, but properly, and I’m panicking a little over the details.

God bless you all and thank you.