Could I be Preg. a week of sex before period starts and Missed period the next month?

Is it possible to get pregnant when having unprotected sex a whole week before period? and had period 3 days later but the next month with a missed period? Im very curious because i've been having pregnancy symptoms lately [ light brown/red spotting 3rd days during missed period ], [headaches out of no where, craving for specific food, sore nipples and it pops out more than usual, and mood swings, bloated (had a little tummy)] it's been 6 going to be 7 weeks since my period started [Jan. 1st] but 2 weeks since my missed period. Is their a possibility i can be Preg.? i took a preg. test today this morning but it said Neg. so im not sure if im preg. or not, or maybe i've just been stressing out..