If my sister and mom has no blood clotting disorders and had no clots in pregnancy. are my chances of clots in pregnancy low?

Low: If you do not have a family history of blood clotting disorders, then your risk of blood clots during pregnancy, and throughout life, is very low. Birth control pills and smoking is a deadly combo for creating blood clots. I assume you would not smoke at all and definitely not during pregnancy.

Low risk : Thrombophilias, or clotting disorders, are rare, but can be hereditary. So I would say your risk is very small.