you can get a pregnancy test to see. The instructions tell you to use back up protection for at least two weeks. Pregnancy is possible, BUT some birth control lessens your period, and some get rid of them all together. I'd start with a test, if if is negative give it a week, the meds might have threw it off.
yes it's possible that you're pregnant, but do not freak out yet :-) wait at least a week or 10 days and if you have not had your period by then, it's time to take a pregnancy test. But I don't think you have to freak out even if you are pregnant since it hasn't been so far gone it's very easy to have an abortion...
I would say it depends on if you missed any pills... the new pill may be effecting your period or may be affecting your body diffrently than your previous pill... i have always had issues with birth control pills and was switched from brand to brand and it always affected me diffrent... i would say that if you havnt gotten it within a few days to call your physician or take a hpt. but as long as you didnt miss any pills you should be ok... or at least thats what my dr used to tell me...hope that helps a little.