Cow - that is great that you avoided the hard stuff! How impressive is that!
Now, about diet soda..... Surely you have heard its not a good thing. The artificial sweeter is poison. Plus it fools your body into thinking it has had some calories when it has not. Which then leads you to have incredible hunger later. If you are going to have a Pepsi it is best just to have a Pepsi. Don't make it worse than it is by making it a diet Pepsi.
Getting off the soap box now. Congratulations again on working sober!