Originally Posted by
atomic sagebrush
It is possible that you ovulated later than you think and that this is a new pregnancy that hasn't shown up on tests yet. It is also possible that it's a chemical. But, it's ALSO possible that you still haven't ovulated yet and your symptoms are from a hormonally "weird" month (and it's even possible that you HAVE ovulated and it's still just a weird month)
Because progesterone rises post ovulation, sometimes, in some months, especially when something is hormonally different (like when you're on a sway diet) you may notice more intense symptoms in the 2WW even when not pregnant. I know this is hard to believe but because both the luteal phase and pregnancy = higher progesterone you can have an overlap of symptoms. I myself have gotten nauseous to the brink of throwing up in a couple months after O, even when there was no way I could have been pregnant.
So while I know this is an irritating non-answer, the truth is, we don't know what's going on, there are several possibilities, and we can't tell for now which one is the real deal. Most likely case scenario you're going to get a proper flow in a day or two and then we can think back to about 14 days earlier and that's likely when ovulation occurred.