In some ways I think some people are being way too harsh with you. The urge to procreate is, after all, a basic one. Let's face it...most of us wouldn't be here if everything about our conception was 'perfect.' C'mon.
As for 'tricking' the boyfriend...well, frankly, he
probably knows that sex can result in pregnancy

If someone really, truly does NOT want to conceive a child, someone shouldn't have sexual intercourse. It's the old 'Don't like the heat, stay out of the kitchen.'