So frustrated!

My period was supposed to be around the 20th and it never came. I have been spotting pink and brown since Saturday! It barely gets on the pad. I've taken 4 hpt (last one on the 29th) and all bfn. My periods are usually really heavy with bad cramping. I see the doc on the 16th, but i wanted to see if anyone has gone through this and ended up pregnant? I hate not knowing what's going on.