Yes , See Were In January Already And I Never

Yes , see were in January already and I never started my period for the month of December. At first i wasent concerned because i have an irregular flow , but for about three months straight i had my period regular , would start on the 20s and end by 30s of the month. My last period was on Nov.27-30. And i was scared so i took a pregnancy test but results were negative. I dont know what to do.