How long does it take to tell if i am pregnant and is it easier to get when i am bout to start my period ?

ok well me and my bf had a few days ago and i due to start my period soon he cam in me about 3 or 4 times is it easier to get preg when your about to start your period cause my stomach fells weird and has a tight felling like its pulling i keep thinking i am bout to start but i anit started yet and i am worried please help me out