One week is not very long. Usually it takes 4 to 6 to 8 weeks but everyone is different and sometimes you can feel it is a week or two.

In my experience if an antidepressant works for me I feel like my normal true self. I feel a much wider range of emotions compared to being depressed. I am not always depressed so I know what I feel like when I feel what is normal for me. It never feels unnatural or altered or artificial. I have had lots that didn't work and in that case I can't even tell I am taking it. It just does nothing. That is just my experience and everyone is different.

Maybe give it some more time and then make a decision. One week is not really enough time to get up to a constant therapeutic level. The fact it is working on your anxiety is a good sign. For most people they don't work for anxiety. They don't understand fully how they work. The chemical imbalance theory is only part of the picture. It's possible they correct something amiss for some people and it is not unnatural. Everyone's experience is very different though. Its totally up to you if you want to take it or not. I have never thought of it as an artificial happy though.

I think a lot depends on what the underlying core cause are. If they are primarily medical and the stress that goes with that then maybe there are other means to deal with that. It is common for medical issues people are going through to cause anxiety and depression. Heart surgery for example.