Breastmilk production

Currently at 30 weeks of pregnancy normal pa ba na at this rate eh hindi pa ako nakakapag produce ng milk? I'm a little bit worried kasi I'm planning to breastfed my baby tapos until now parang wala pa akong gatas na napproduce unlike sa sister ko na 5 months pa lang may napproduce na sya. Is this normal or may mali ba sakin?