I've never taken that SSRI specifically, but I've taken many others. They take quite a while to act, and once they do in my experience you can feel all sorts of out of it for awhile on them.
In my experience ( again not a doctor) the SSRI class of drugs can help immensily buts its about dosage and side effects. All of them have the same action in theory, but for me I found some of them to have more side effects then others. I also had others that helped more, but came with more side effects and ones that helped less and had both a ton of side effects and ones that had no effect but no side effects.
I hope I am not confusing you, the point I am making is the medications are going to effect your brain chemistry. In the past I have been on medications that make me feel exactly how you descibed and that you need to find one that makes you less depressed, feel better, less anxious whatever, but that the side effects aren't too much.
Scientist still don't know exactly why SSRI, SNRI, work with depression anxiety, they can only prove with trials that they do in fact work, with that in mind dosage, type of medication and side effects are key. If you aren't comfortable with a medication ask to have it changed or have the dosage upped lowered what ever, the ultimate result should be a reduction in the symptoms you are experiencing in my life that takes a lot of trying different medications and dosages. Good day and good luck.