I'm two days late and I have a migraine...

My period is ALWAYS on time and I'm used to headaches but never this bad... I had sex during my fertile period (I know, I know but I'm currently in a LDR and I didn't get to choose when I saw him this month) and we generally use condoms only. He's used to cuming in me because we've never had an accident with the brand of condoms he uses. He always checks after the fact to make sure they are not broken. Could he have missed a rip and here I am knocked up? Or am I WAY overreacted?