your situation is exactly the same as mine. my family also dont serve the Lord, they all think I am nuts! The only thing we can do is pray for them and God will do the rest. He will bring our families into His kingdom. They are in His hands now and he will answer our prayers, God knows that we want our familes to be saved, dont worry about it anymore.
I just felt I had to encourage you. Hope that helps
Psalm 145 vs 19 He will fulfill the desires of those who reverently and worshipfully fear Him. He will hear their cry and will save them.