Iron Supplements ?

Rose

My iron used to be on the low borderline before pregnancy, I am in the second trimester. I wanted my doctor to check it now, but the dr said “My hemoglobin level is normal, so no need to take iron now, they are going to check it on 28th week.” I watched other doctors saying that “for every pregnant, she is lack of iron or not, it is so important to take iron supplements from 16-20th week on forward to keep blood level good”. I am taking vegan prenatal once a day mutivitamin including 18 mg iron. Do you think I need to start taking additonal iron supplement from now? Do you know any tablet or liquid natural (vegeterian or vegan) iron supplement? For a start, how many mg iron do I need? If you use one of them, do you have side effects?