answers please

Markeenia
Ok so I've never posted on here before, but I need some advice. My last period was Dec 6-11. Today is Jan. 20 and I have yet to see my period. Last week Wednesday through Saturday Jan. 11-14 th I spotted everyday once a day. Tonight I took a cheap $1 test and it came back negative. So my question is, should I wait to take another? How Long? Should I go to the doctor? Or should I just wait to see if my period come? Has this ever happened to anyone before and they were really pregnant?