It actually sounds like you are so stressed out about the possibility of being pregnant, that you were making yourself physically sick. Now that you are better, it is probably still stress-related if you haven't had your period and have two negative pregnancy tests. Are you normally regular? Stop thinking about the possibility of being pregnant and you will see that your period will come but the more you stress, the longer you'll keep waiting for it to come.
One thing I cannot stress enough though: If you are young and unprepared for a child, please do not actively engage in sex. If you still choose to do so, use protection no matter what. A condom can and will protect you against pregnancy and STD's. It is not worth taking chances when it comes to either one of these matters.