I have once mocked god by believing into false teachings? Is it Blasphemy

When I was younger, my knowledge about god was very weak. I thought that there was no god, and a years later after thinking like that I realized that he truly exists. I thought that I have to take my act together and start going to the church. I did, but one sin caught me like a fish with a spear: Blasphemy. All I knew is that insulting god is considered a unforgiving sin and now I live like this everyday trying to find awnser for what I did. Did I really commit it? Or am I going to hell now? I have so much questions and so little understanding. I fear judgement of a God. I fear hell, I even think fearing god is a sin. I need help. I need someone to talk to.