Late period...

Autumn

Okay, I’m now a week late and I have some thick white discharge instead of my period. I also have a few other possible pregnancy symptoms. I tested Friday morning at 5 days late but it came back negative. When should I test again? I haven’t been irregular in a while my period has come within the same two days the past three months (that’s when I started using this app.) Oh, and when I do test again what would be the best test to buy?