Hi,
i think i've talked to you before and you're on marvelon right? (it's called desogen in the states for any americans reading this and seeking the same advice) anyways, the deal with marvelon is that it's monophasic, which means that all the pills contain the same amount of hormones, as opposed to triphasic pills like ortho-tri cyclen, which have diffent levels per week to try and more closely mimic your body's natural rhythms.
With triphasic pills breakthrough bleeding is common as a result of the drop in hormones from the third phase back to the first phase, since your pills are monophasic however, there is much less chance that you will experience btb because you're just keeping your body at the same level or hormones that it's used to. This is not a promise that you won't, you might, but on a monophsic pill the chances of btb is significantly reduces vis-a-vis a triphasic pill.
Hope that helped,
~laura

Alright, thanks.. Guess I just have to see how it goes!

Yeah, I tried to "skip" my period on the combination pills and I just ended up spotting for a week or two, and it was useless. However, now that I am on nordette (the same hormones all month) I can successfully skip my period. I still spot for a little while and get cramps, but it can be done. For me it is not worth the trouble, but if it was something important at least I know it can be done. You just have to let yourself have your period every third month. I hope it worked out for you!