should I have my Anti-D earlier? anyone a doctor/nurse

Chelsea • Oliver-James 19/05/2016💙 Harvey-Kai 27/08/2017 💙Darling husband 14/02/2013 💙 💋perfect💋
I am Rhesus Negative, ( O- ) blood group, and when I'm pregnant I need anti-D jabs.  I have my midwife appointment today and she said I won't need them until at least 28 weeks?? With my first I'm sure I had my first at 16 weeks. I have already had 2 early scans for bleeding. Luckily it has stopped. But I'm not sure if this is correct. Can anyone help.