Try to cut down slowly, I know it's hard, but your body will thank you. As most of time what's in the diet soda is worse on your body then if you drink the one with pure sugar in it. The chemicals they use to make it diet are really tough on your body, and you won't notice it right now but drinking 3 to 6 a day will catch up to you and when it does, it won't be all the pretty. But then again if you got extreamly good luck, you maybe able to drink that soda and never have a health problem. But that's one heck of a gamble, if I were you, I'd much rather put every single penny I'll ever make in a slot machine and see if it will triple my earnings.
Do you know that some diet sodas even have formaldehyde in them? That is really yucky, as it will actually preseve the fat cells just like it does in dead people. But also means it makes it a lot harder to lose weight. Not to meantion they use it on dead people and things to preseve them. And the fact it can tear up your kidneys, liver, and gallblader.
Now will something bad happen to you if you keep drinking your soda? Your guess is as good as mine. you may have the luck, and you may not have any luck.
I know for the fact living has it's own toxins and deadliness to the body, and you basically have to pick your poison, so I always tell people, if your going to do something bad, know excatly all the consequences, and be willing to accept every single one of them. If you are then go ahead, if your not, then find something else.
Yes snacking is bad, and you are probably doing it because you desire something sweet. So try to chew gum, or eat either something sweet or sour. As for some reason both will take care of the craving for something sweet.
Or simply just start cutting down a little at a time, like tomorrow cut out half a can and go with that for a few days, then cut out another half a can, so that should be a whole can gone and then continue on, until you don't need it any more. You'll also fine that once your body gets use to it, it won't need the cafine and you are actually more alert all the time.
Good luck and best wishes,
Kit