Brief Answer:
I will try to help...
Detailed Answer:
Your question is extremely common: the patient with a delayed period, symptoms of
pregnancy, and negative tests. So the symptoms are usually not related to pregnancy. The presumption, based on the fact that they are new symptoms, is that they are related to your cycle.
During the second half of your cycle,
progesterone is the predominant hormone. Women have symptoms during this half of the cycle that are varied, but follow familiar patterns if you ask them about them. Breast tenderness is very common. A heightened sense of smell is less common, but not unusual and I have had many patients experience this during the latter part of their cycle as well. Finally,
nausea - while this is not typical of cycle related symptoms, it can certainly be associated with elevated levels of progesterone.
The only other thought is this: In any woman experiencing irregularity in her cycle, tests of
thyroid function should be checked. Thyroid disorders can also present with symptoms such as you are describing, and usually manifesting primarily as extreme irregularity in your cycle. It is also remarkably more common among women.