Cycle day 47/ 20 dpo. Need advice

MrsCeo
I should have received my period on Dec 28, 2015, but there was nothing I have taken 4 test since this Monday (1/11/16) the last test I took was an extremely vvvflaint line. Waiting g to take a look test on Friday can't wait. No sore boobs just very nauses at times. If I'm not pregnant what can cause this and I have not been stressing.