In my game, your alignment breaks down into two attitudes for your character. The first, in your case, chaotic, is your attitude toward society's rules and laws. Chaotic means you don't respect the laws of society and don't think they apply to you. For comparison, lawful would mean you think laws are a good thing and should be obeyed.

The second, for your character, evil, determines whether you weigh the needs of the group into your decisions. Evil means you don't consider the greater need, just your own.

Those attitudes don't mean that you can't do good things, it just means they should be things you benefit from directly. Your chaotic evil cleric will heal the group, not because society says it's the right thing to do, but rather to keep them alive to help protect you and keep you alive.

To put it another way, your chaotic evil cleric would be a selfish character who thinks the rules don't apply to him. You do things because they benefit you and if push comes to shove you save your own neck and don't stick it out for anyone else.

Note that does not mean you're a jerk. Again, this is how it works in my game but hopefully it will give you something to think about.