Hii.. congenital septate uterus and arcuate uterus , both are two different anomalies of uterus. As you have mentioned about size it could be probably septate uterus. Usually it won't affect your menstrual cycles (some might experience painful periods). Most of these anomalies go unnoticed or can be found incidentally during caesarean section. Some women might experience difficult in conception or experience repeated miscarriages. Only in such scenarios it can be removed by hysteroscopic approach. Usually outcome will be good. So no need to take much tension.