I am a mother of a 11 month old baby.. and i too used to feed for long durations, prior to 6 months completion, 1.5 hours even. Doctors write "exclusive breast feeding" because that phrase means to feed ONLY breast or forma milk for 6 months (180 days completed). To start solids and other foods after this 180 days + solid readiness signs. Universally, formula feeds is the ACCEPTED ALTERNATIVE to breast milk. No doctor says don't give formula feeds. There are many babies completely dependent on formula feeds from day 1. Breast milk has less chances of infection and contamination, hence its deemed the best. To increase milk, you have to be the healthiest, happiest and drink lots of fluids. Your mental and physical state have to be good. You can also try expressing breast milk using a pump to stimulate the same. That way you can tell how much milk you are getting per breast, per feed. Your breast feeding techniques also may need altering, along with the positioning and burping. There is no fixed feed amount that a child drinks. It is all dependent from baby to baby. If you want to discuss this further, book an appointment. You can follow me on Instagram @pediatrician_india for more helpful tips ! Take care !