Can having low iron stop you from getting pregnant?

If anemic. If your iron levels are low enough to cause anemia (low hemoglobin) then the answer is yes. Taking a prenatal vitamin with folate (folic acid) and iron may be enough to get those levels up.
Unlikely. Iron-deficiency is an unlikely cause of infertility. However, if one is severely anemic that has systemic effects, then it is possible to decrease one's chance for successfully conceiving, but is not absolute.