Need some answers.. Please help.

Ali • 18. I`ve Been with my bf for 3 years. Not really ttc but not trying to prevent it
My period is 5 days late. I was suppose to get my period around the first of this month but it hasn't came yet. Me and my bf had sex 2 weeks ago we need use anything and he didn't pull out, I'm waiting for pay check to buy a pregnancy test. Not really sure if I've had any symptoms. 
The second day It was suppose to be here I was dizzy and nauseous when I woke up, third forth and today I've felt sick and tired, I'm ready for nap around 1:30 2 in the afternoon. Not sure if it's a stomach virus or what please help.. And when I do buy a test what would be the one to get?.. No negative comments please