To young but wanting

I am 17. I will be 18 in April. I am way to young to be wanting one of my own. A week ago me and my boyfriend of almost three years had unprotected sex (multiple times) and no precautions were taken when he came. My boobs are extremely sensitive and I have a bunch more things that point out that I could be pregnant. I took a test today and it came out negative. I'm supposed to get my period sometime this week and in all honestly, I don't want to. I almost cried when I saw the results. I feel really disappointed. I know I shouldn't but I do. My friend told me to see if it comes this week and if it doesn't take a second test this weekend... Any random advice..