Salam alykum sorry for late reply
1) do tawasul with Hazrat Zehra SA for marriage
2) in ur case if you find good shia man for marriage then you don't need permission from ur parents
3) you have to be strict regarding ur upcoming life if you for weaker and more inclined to ur family then might ur kids and life will be difficult as you told that they hate shias
if you have difficulties to find a good option for marriage then let me know where you live might we can do anything for you
if you don't want to share ur info here then I will give u personal email address