First of all, try to keep your cool. Being worried about being pregnant can cause stress, and stress can make your period later than it is supposed to be. So basically, your period could be later because you are stressed, and then you'll just be freaking out even more. So take a breath, be calm, and relax. If you want to take a test in a couple days and then take one a few days later, than by all means do that to give yourself some peace of mind. However, don't if you think it will stress you out more. If you are feeling stressed about it I wouldn't worry about pregnancy until (since you are on the pill) a few days after you are supposed to get your period. At that point, take a test. Take it before the mark of when you would start your next cycle of pills. If it comes up negative, you're probably not pregnant. If at the end of the week you still haven't gotten your period, call your doctor just to find out whether or not you should still take your pills as directed. Do this before you actually need to start taking the next round of pills, otherwise you will be thrown off even more. Even if you do take the tests the way you proposed, be sure to still call your doctor if you should continue your normal cycle of pills if you haven't gotten your period by the time you are supposed to begin the next cycle.
To answer your next question, IF you are pregnant, there are several options you can explore. There is, of course, termination of the pregnancy, which can be done before the fetus has gestated for 12 weeks. However, I would only suggest this option if you are
100% okay with the idea. i have known people who have had abortions only to have it weigh heavily on their conscience later in life, and even cause them to pass negative judgments about who they are as people. So think carefully about this option before you choose it.
If you are comfortable with it, morally and emotionally speaking, it's actually probably the easiest option. Least expensive by far, anyway, and with the least amount of pressure on your body and your emotional health.
There is also adoption. You can have a closed adoption, in which the adoption is arranged and you don't have contact with the child again, or you can have an open adoption, where the adoption is arranged and you can still receive pictures and letters about how your child is doing. I think in some cases it can even be arranged that you get to see the child, though I don't think it's very common, and you wouldn't be able to see the child as its mother. Many adoptions are open these days, but there are still closed adoptions, too. The choice is really up to you. Adoption is a wonderful example for people who are in your situation (not financially independent enough to care for a child, not done with their education, etc.) who don't want to keep the baby, but who do want to give birth to it. There is some more physical taxing to your body and emotions, not only because pregnancy can be an emotional time, but because the pain of giving up a child, even if you know it's the best thing for everyone, can be very, very hard. Still, it's another option for you.
The last, of course, is to raise the baby yourself. This, of course, is the most financially, emotionally, and physically draining option. At your age, it's unlikely that you would have a job in which you can comfortably support a baby, considering they are very expensive to care for. Your future would be forever changed for you and your boyfriend; once you commit to parenthood, it's a life long obligation. You will be responsible for your baby until it is eighteen, really even beyond, if you consider paying for their college education and helping him or her get established as an adult. While it will not be impossible for you to get through college, your college career, IF you can manage it still, will become much more prolonged and much more difficult to get through, and probably put on hold for a while. It's very hard to do homework and pay attention in class the next day if you have to wake up every hour to a screaming baby all night long. Basically, your life becomes dedicated to your baby. Your social life will become almost non existent for a while, and there are other consequences, too. Like I said, big life changes come with a baby, and many young parents think they can handle it only to have it turn out they have trouble balancing everything. After all, at this age you are still growing and changing as an individual. This process will be severely impacted by the presence of a baby.
So far it seems I've painted this option out to be negative, but it is not all bad. While many young parents do struggle with children, many also find joy and satisfaction in being parents. It can be so rewarding and filled with love; it truly is a special thing to be a parent. It has many of its own blessings and merits that can be just as important as all of the things I have mentioned above. And the two CAN be balanced. While it is difficult, it is not impossible.
My best friend gave birth to her children when she was not much older than you are. And she went to college. It took her years, between having to withdraw to take care of her children and life's other pressures, but after about 16 years she finally earned her degree in Computer Design and Graphics. She has two beautiful teenage children now, a great job, and she is very satisfied with her life. She is my true life example of someone who entered parenthood who, while she may not have actually been entirely prepared for parenthood, especially as a single parent (which she was from the time they were babies), managed to succeed and find much happiness with herself and her children.
So really, all of the above options have their benefits and drawbacks. You can also research all of them in more depth on your own. There are plenty of other sites that can give you much better information than I can.
IF it turns out you are pregnant, you can begin researching these options and see which one fits you the best.
So for now, try to relax and focus on your studies and such. Things will work in their own time.
Good luck.