This is exactly what I've been worried about her demons army since the beginning. But, now that the author explicitly spills this problem, she also give SYX the method to solve it: Little Feng, Dou Dou, and herself can use their devil power to fight the control over her demons army from the devils. If Little Feng and she have too little devil power, Little Dou dou must have enough power to do it after three years.

Yeah, feels annoying to read all this pre-written speculation ?

Being told it and understanding the implications are two different things