The risk is said to be that if the baby implants on the uterine septum (if you have one), it might not get a good blood supply and you would lose the pregnancy. But the jury is still out on how much the uterus' shape affects the rate of pregnancy loss. Some women who have an unusual shape of uterus do have miscarriages or difficulty conceiving, but so also do women who do not have an unusual shape of uterus, and so far there has not been any study showing how many women have them out of the population. (Let alone a study that rates a whole lot of women on their uterus shape and then follows up to see if their miscarriage rate is higher than average.) I don't think anyone even knows how many women have anomalous shapes of uterus, many might and it is never detected. All of the heart-shaped uterus studies I have seen have begun with a woman who has had a problem, and then they have determined that the uterus was or wasn't an unusual shape. That is no way to judge whether the uterine anomaly caused the miscarriage or not.
I wouldn't think you are at risk for anything. I'd google to see. I was told I had a tilted uterus but both my mom and grandma have one and it doesn't mean anything.