I think you should keep on taking the pills throughout your pack. You will probably mess up your cycle more if you stop to have a "regular" period now...
I don't know what kind of pill you're on, but if you are on a triphasic pill, that might be why you're having trouble with skipping -- since there are different levels of hormones each week, you would have gone from the highest dose in week 3 to the lowest dose of active hormones, in week 1. So the drop in hormone levels might be what is causing your spotting.
Also, if you are on a low-estrogen pill, it may be more difficult to skip a period, because the estrogen is typically what prevents breakthrough bleeding/spotting in midcycle.
And even if it isn't one of these two reasons, I have read that not all people are able to skip their periods on the pill (I don't know if you have done this before)... also, if it were something you wanted to do regularly, your body might need to get used to it...
Overall, there's nothing to worry about - if you have been taking your pills correctly every day, then you don't need to worry about pregnancy. Spotting is a pain, though, and it's really too bad that you didn't get to skip your period.
I hope the spotting stops for you soon!!!
-Mirabelle