Help??

So my period was suppose to start on Monday. It is now Thursday and still nothing. I had sex with my SO during a fertile day last month. We do not use condoms and only use the pullout method. I had a period last month but it came a day early (which is extremely rare for me...I'm very regular) and was extremely short. Maybe lasted 3 days (which is also rare). I'm 24 with a 4 yr old daughter.....think its time for a test?? I'm extremely nervous.....