Amigo, your salvation is contingent upon the life and death and resurrection of Jesus. If he did the things he said he did (and we have every reason, both historically and biblically, to believe he did), and the things he said he was, then He
when you ask Him. And when He has you in His hand, He's not going to let you go for anything.
If this world were to explode into a thousand pieces, still He would hold onto with a grip surpassing death itself. When we're saved, God ties a rope onto you, not the other way around.
So if you asked Him to save you, and believe that He was who he said he was and rose from the dead, you are saved. Nothing you do, don't do, or mess up on will change that. Remember, God knows past, present, and future; He knew your every thought, doubt, sin, fear and mess up from the beginning of creation. Nothing you do can throw a curve ball at Him and cost your salvation, for I am convinced that neither death nor life, neither angels nor demons, neither the present nor the future, nor any powers, neither height nor depth, nor anything else in all creation, will be able to separate us from the love of God that is in Christ Jesus our Lord.
And unless somethign freaky is going on, you too are a created thing.
To add onto that, if we are faithless, He remains faithful. For he cannot disown himself.
Everyone has doubts and fears, but at the end of the day, our salvation is entirely relying on Him, not us.
And that is a comforting thought indeed.