Blood test or wait it out?

My last period was non-existent (I am 3 weeks overdue, 1 week away from when my next is supposed to start). I have taken several negative pee tests. I have been having mild cramping/bloating and back pain. As of 3 days ago, my boobs are sore and I'm nauseous.

Should I go to the doc for a blood test or wait and see if my next period comes?