Because pregnancy symptoms and hormone/period arriving symptoms are almost identical, its almost impossible to guess.
If your period isn't due for 2 weeks and you had your last period as normal, it would be very early for you to be getting pregnancy symptoms, those mostly start around the time your period would be due.
At ovulation time (around now) you can have sore breasts and a little bloating too. The light headedness, headaches and nausea could be due to a bug of some kind.
As for the periods being much shorter than before, you could maybe ask for a blood test at the doctors, they will check to see if there is any hormone imbalance that has caused your periods to adjust.
So while you could be pregnant I'd say it was unlikely at this point.
I wish you all the best x