Can you not eat shellfish? I have this same situation (I'm not a Copt, I'm Chalcedonian, but it's the same fasting). I eat shrimp most every day.
Also, brown rice protein shakes (mentioned by therajraj) are a great idea. A good brand is Sun Warrior, if a little expensive. You can shop around on Amazon. I use mine in the morning with some fruits, usually blueberries.
Beans will provide you with some protein and lots of fiber. Natural nut butter will give you some great fats and a little bit of protein too.
Biotest's L-Leucine is NOT derived from animals (according to the label), so if you have enough money, I would recommend getting some and using it extensively--stuff is awesome.
Lastly, make sure everything else is dialed in, not just diet. With meat, it's easy to just out-eat your problems on a bulking diet, but it is harder during fasting periods. You have to make sure you're resting enough, getting enough of the right micronutrients, getting enough fiber, etc.
Have a blessed Fast.