Breast Milk

How did you know na nagkakaron ka na pala kayo ng breastmilk? May iba kasi sabi parang may kusa na lalabas kaso sakin wala po and I'm 8 mos preggy, first pregnancy ko din. Pero madalas sumasakit breasts ko, minsan left and minsan right. Di sila sabay sumasakit. Worried ako baka wala ako maproduce na breastmilk kay baby