You sound a WHOLE LOT LIKE ME. The zoloft will not 'kick in' for another week, and even when it does, it will be a slow, drawn-out sort of help - a bit better each day. .5 mg of klonopin is a low dose. But it can still make you feel lethargic, lazy, sleepy. Plus, if you still have problematic anxiety, you will need a higher dose. I have noticed that after years of taking Klonopin, it no longer makes me feel so tired - I simply relax about things, and it keeps the panic away. I would say that the tiredness is temporary until you adjust to it. See your doctor about this.
Were you put on these three meds all at once? If so, that's odd -- how can you tell if only one would have worked if you're put on three drugs at once? Klonopin can make you very tired when it wears off, as can all benzos, although it lasts longer in the system than other benzos and so has less of a problem there. Remeron really slows the metabolism (big weight gainer because of that and its propensity to make people crave food) so it could be making you tired as well, and starting any antidepressant such as Zoloft can be sedating. So three sources of possible sedation added at one time -- I guess it would have been nice to just see if the Zoloft kicked in and worked first before loading up.
I don't Know but maybe the Zoloft needs more time to be noticeable for you. I don't know anything about the other two meds. i wish you the best.