I know just how you feel. I just did my first flush last weekend, after reading this forum since last February. Except for the unpleasant taste of Epsom Salts , it wasn't even half as bad as I had expected. As a matter of fact I wondered what I had done wrong to NOT feel bad. I'm just counting my blessings and preparing to do it again next weekend. I didn't get a whole bunch of big stones like some people do, but when i saw what did come out, I was glad it wasn't in me anymore.
Good luck, and try not to worry too much. Let us know how it goes.