The best way to overcome doubts is through knowledge. Seek certainty and confidence by doing more research about the core issues (don’t get lost in details). Go back to the basics and that’s how you increase your certainty. For example, these are some core questions:
1- Would the Prophet (s) leave this Ummah without appointing someone to represent him?
2- In Hadith al-Thiqlayn which is accepted by all Muslims who does the Prophet (s) refer us to for guidance?
3- Does the Qur’an tell us all companions were good and that we must follow them all?
4- Those rulers who came after the Prophet (s) did they really follow his teachings and implemented Islam properly?
Develop certainty about such key questions.
Also, I recommend seeing the following videos:
And this playlist (I know it’s long but it will help you reach that يقين Insha’Allah):
And if you have not read Tijani’s book ثم اهتديت Then I was Guided I recommend you read it.
Also, I don’t recommend you inform your family that you have become Shia. At least not now. They might give you a hard time and put severe pressure on you. Be patient and Allah will help you. Life is a trial, and the truth doesn’t come easy, but you are blessed for being guided by Allah. Realize the value of this blessing.