Best type of pregnancy test to buy when you're 2 days late

I'm currently two days late for period. Mine r semi irregular but I'm pretty sure I ovulated the beginning of this month (I check my cervix n everything) . I'm not on any birth control. I took a 89 cent one from Walmart two days ago came back negative. Could I have tested to soon or do I need a better one. If she doesn't show by Friday I'll buy a better one. I just have really sore boobs sometimes I get nauseous & today I have flu like symptoms. I'm always tired. Usually I have cramps by now. Instead I just have those symptoms n white discharge.