am i pregos? HELP.

Becca • here to track the bloody beast inside
okay so, i just had sex w/my boyfriend like 2 hours ago, he came inside & now i'm experiencing bad cramps. its the first time this has happened, but its also the first time i orgasmed w/him. plus we are both feeling a little sick.
BACKSTORY: he is very low fertile, he usually cums inside me (but i scoop it out afterwards), he's came inside all hes exes for years but nothing happened, i'm unsure if i am high/low fertile, this week is my fertile window. 
i have just heard stories of women knowing when they have conceived & i'm nervous. right after sex, i went to the bathroom to take out the cum and clean myself, but i'm nervous now & need your opinion...