Am I just being paranoid?

I am scared to death. I am 17 almost 18 and I am very scared I could be pregnant. About two and a half weeks ago my boobs started getting very tender and they are still that way, some days more than others. Last week I was having sharp, but not so sharp that it was unbearable, pains in my stomach (sort of like hunger pains) but those are gone now. I am always tired as well, but that may have something to do with high school. Also yesterday right after I ate I randomly threw up what I ate, but never even felt bad even though my stomach has been a little upset most of the time for the last few weeks. I haven't wanted to take a test because I want to get a good reading and I can't remember exactly when I got my period last month so I think I'm just going to wait untill the end of the month to take a test. Could I be pregnant? and if so how do I tell my family without them freaking out?