No, you can't lose your salvation by not giving your testimony. After we're saved we're sealed by the Holy Spirit. No, "publishing" what Jesus has done for you doesn't mean you will receive or perform miracles.
(Ephesians 4:30 NIV) And do not grieve the Holy Spirit of God, with whom you were sealed for the day of redemption.
Psalm 68:11 doesn't say what you wrote. This is what it says.
(Psalms 68:11 NIV) The Lord announced the word, and great was the company of those who proclaimed it:
You are getting me wrong brother. I am not talking about salvation but your Miracles. A good example is the ten leprosy men Jesus healed only one come back to give thanks of what Jesus have done for him. Scholar has it that the remain nine died in leprosy.