Well if you have still a week to go til your due on its unlike that its morning sickness and all that jazz.
Tests are expensive... So I would wait till your period is due and probally see if its late.
But if you worry about it you chance stressing your self out knocking it out a few days.
But on another note. Something you know people are gonna say, you guys really should be using some form of contraception unless you are activly ttc.
Good luck