You should have been born catholic, then you could do whatever you want and just go to confessional afterwards 
Anyway, it doesn't sound like atheism is for you. Not if your belief is unshaken and unshakeable.
Atheism probably wouldn't solve your dilemma anyway. You wouldn't suddenly feel free to commit any deeds that you wanted to - this is a misconception.
Atheists actually are much more ethical and behave more morally than religious people do. Just look at the rates of atheist vs believer in prisons.
I'm guessing your solutions will lie within the context of your faith. I'm hoping you find it soon, because it sucks that you aren't feeling happy and at peace.

Anyway, it doesn't sound like atheism is for you. Not if your belief is unshaken and unshakeable.
Atheism probably wouldn't solve your dilemma anyway. You wouldn't suddenly feel free to commit any deeds that you wanted to - this is a misconception.
Atheists actually are much more ethical and behave more morally than religious people do. Just look at the rates of atheist vs believer in prisons.
I'm guessing your solutions will lie within the context of your faith. I'm hoping you find it soon, because it sucks that you aren't feeling happy and at peace.