VERY CONFUSED>> NEED ADVICE

Last month I had sex 3 days before my period using the withdrawal method and my period came as planned. Is it still possible for me to be pregnant? my period is 2 days late and its never late its usually early if anything. my brests (nipples) are very sore and have darkened in color and have also enlarged. I feel naseau in the morning and afternoon. it is possilbe for me to be pregnant? should i consider taking a home pregnancy test??? please help, im srry if this is a dumb question but one of my friends told me that i could still be pregnant even though i had my period lat month.Is this true?? should i take a test to be sure?? plzz help!!!