Help me please--spotting (TMI warning)?

I spotted for one day exactly 1 week before my missed period. It wasn't even enough to call it a "flow". There was only a slight, light pinkish amount of blood only when I wiped...there wasn't even enough for a need for a panty liner. Then all of a sudden it stopped within the same day. The next day-nothing. Then, the following day after that, it did it again...and it's been doing it off and on for the past 6 days up until today (which is the day after my period is supposed to start). Today it is slightly (and when i say slightly i mean SLIGHTLY) heavier of a flow, but not much. I do not take any prescription medications nor am I on any contraceptives of any sort. I am 21 years old. I have never spotted before like this and I am just wondering if this is normal. I have a Dr.'s appointment on the 9th (this thursday) but I am just wondering how many women have gone through this, and if it turned out that everything was ok. I'm just worried that something is wrong and I don't have the slightest idea what to expect. And FYI--please only answer if you have gone through this or know of someone that has before, and if you actually have a valid input...like I said, I have a Dr.'s appointment already so don't just tell me to "go to the dr." because, i reiterate, i already am. Thank you for your time.