Suggest Diet Plan To Increase Breast Milk

My baby is 3 weeks old. I am breast feeding him. Since three days he started crying after few min of breast feed and leaves the nipple. If I latch him again he sucks for a while and starts crying loudly. If I squeeze my breasts milk is coming in drops and after some time it stops. My mom is telling that my milk is not enough for my baby so she suggested to give formula after breast feeding. But I just dont want to make him used to this formula. I am so depressed. I just dont want to give this formula. I just dont want to give this formula. Pls help me.