My AF is very regular, but sometimes it throws me off somewhat, it is completely normal to be late, even if it doesn't happen very often.
A lot of times AF symptoms are much the same as preg symptoms, which is what I experience. I find the sickness doesn't kick in until about week 6 of my preg, nipples don't darken until later on, but do have tenderness of the breasts, as for cravings, only happens to me when AF is due not when I'm preg.
There is a 50/50 chance, but if the condom didn't break then there isn't a huge chance of preg.

So why all of that?! It could mean anything really, you need to just get a test, then if it's neg and you're not ready to start a family as yet maybe you could have a look at contraception options that will work for you both.

Good luck with it all.