I have never actually lost this game. Closest I've ever gotten was a bad RNG with weather, forcing me to buy the cladding very early. (I've seen it go to week 100, and still not have to buy it)
So what's your setup for your slave training? Do you use mostly the head girl's abilities or train slaves manually? Do you make slaves have perfect skills before you sell them? Do you make use of any of the slave schools?
You're doing something really special here, beating the game with limited use of facilities and a small number of slaves.