thanks for your query.
If you have two negative pregnancy tests, then chances of your being pregnant are very remote.
The symptoms you describe could be pre menstrual symptoms.
To confirm a pregnancy, you need to take a blood B HCG test , and a pelvic transvaginal ultrasound
A lighter than normal period could be due to anxiety, stress, emotional upheaval, hectic travelling, rapid fluctuations in weight, thyroid hormonal disorders, high prolactin
levels, polycystic ovaries
, endometrial hyperplasia
, ingestion of hormonal medications etc.
You need to consult a gynecologist to know which amongst these is the reason.
meanwhile, have protected sex in future.