When do I test again?

Hana

Period is 6 days late. My periods can sometimes be irregular I have obvious period symptoms the whole week before it comes but I haven't had any yet. I took a test that showed negative when I was 3 days late and I was wondering how much longer I should wait to take another test? I really don't have the money to buy a lot of tests. Please note I am not trying for a baby so I don't track ovulation days etc, I am a little concerned.