Re: clear discharge, pregnancy?
Try to relax, dear; if you've been stressing out badly about being pregnant, you probably have made your period late from the stress, or if you have ever experienced irregular periods, it count be haunting you now in your time of fear. Your body can play some naughty tricks on you when you are worried about pregnancy - Altari said it well; pregnancy symptoms do not show up immediately.
As for the stomach ailments and the heartburn...that could just be a "stomach flu", as it's sometimes called. The white dishcarge could be anything, possibly a bacterial infection. Have you ever noticed the discharge your body produces BEFORE your period? I hate to be so graphic, but I also freaked out once, believing that I was pregnant when I saw a thick, milky white discharge coming out of me, but what I didn't realize until much later was that I would experience that change in my body's fluids about 2-3 days before my period would begin; it may have been happening for quite a while in your case, but you just never noticed it until now when you are scared (also, I have read that the discharge during pregnancy can be a yellowish color too). What you may believe to be symptoms of pregnancy can all very simply be a series of well-played events within your body that freak you out. Take it from someone who has also been there...it can scare the daylights out of you, but please don't let it get to you.
My only advice for you is to try to take a pregnancy test to put your mind at ease. You're making yourself sick and your mind is feeding off your paranoia and making you think the worst. Please try to relax, and give your period another chance. I'm not entirely sure why you cannot take a pregnancy test, unless you live miles from civilization (out in the country or suburbs is what I mean :3) or you don't want anyone you know to find out that you are suspicious of pregnancy. But in any case, try to get a test.
I wish you the best of luck in your time of fear - I pray that things will work out okay for you so you can relax and get on with life.