I don't know what's going on!

jessica

I have not had my period since December 17th and I still have not had it. i was suppose to get my next period january 15th but i have not gotten anything. I slept with my husband January 21,and 23rd. I took a pregnancy test today and it came out negative. I don't know if it's too early, or i don't know if my body is messing with me. Someone please give me some advice.