Brief Answer:
Be confident; have a healthy diet and adequate sleep

Detailed Answer:
Hi dear,
Welcome to Ask A Doctor service
I have gone through your query and understand your concern

I will list some points that might help to improve milk output:

1) Be confident while feeding. Always try to be happy and in good mood. Good physical and mental health is very important for adequate milk output (for a proper lactation reflexes)
2) Ensure good sleep, at least 6-7 hours a day
3)Ensure a healthy diet with enough proteins(pulses, dairy items, egg, meat), green leafy vegetables and fruits.
4) Drink enough fluids
5) Treat pain anywhere in the body promptly, especially nipple pain/cracks. Pain , anxiety, sleeplessness- all interferes with lactation reflex and decrease milk output
6) Always breast feed the baby when hungry before giving formula feeds. Good sucking in such feeds promote milk output . Empty both breasts before formula
7)Ensure proper latching and attachment while feeding- good videos are freely available online for this

Also, discard any negative or discouraging commands from friends and relatives in this regard, and stay confident

With these measures, most of the mothers will see good response in few days.
If not, I used to give a short course of Metoclopromide tablets(100mg 2-3 times daily for 5 days), which can increase prolactin secretion and milk output; but this is a temporary measure only and better to discuss with your doctor before this

I hope this answer will help
Let me know if I can assist you further
Regards, Dr Aslam

---