I am having similar problem. I want to feed my baby breast milk, but not enough wet diapers and losing too much weight. and I was very unhappy and worry cause seems like I made my baby boy losing weight (cause I don't have enough milk).
Now I am giving him breast milk (very few, I guess only less than 20ml from both side together) + formular milk. He is gaining weight now. So don't feel bad if can't give the baby breast milk. The most important things are the baby is healthy and you are not worried. Let add oil together!