I ask Allah to help you and facilitate it for you. Some recommendations:
1- Be patient. Your trial requires patience and strength. Take it step by step.
2- Remember that Allah comes before your family. If you rationally cane to believe in the path of Ahlulbayt (a), and you are certain about that, then that comes before your family or anything else in existence. One of our most difficult trials in life is our family. We love them and sacrifice for them, but Allah and the truth come before them. So many people in history did not follow the truth because they didn’t want to lose their family.
3- Increase your Yaqeen in the Shia school of thought so you can be more confident. I recommend seeing these if you have not already:
4- Don’t inform your family you are Shia. One day when circumstances are more suitable you can inform them. There is nothing wrong in hiding that. You are not hiding to deceive anyone—you are hiding to protect your beliefs. That’s completely acceptable.
5- I recommend you postpone marriage for now until you are in a better and stronger position to inform your family that you are Shia or that you want to marry a Shia. Maybe now it will cause excessive stress on you.
I ask Allay to facilitate it for you and guide you every step of the way.