I'm late by 9days, but I'm not sure if I'm pregnant

Haya everyone, 
So I need some advices or resurance. Me and my boyfriend are trying for baby for about a month or two and this month I was late by 9days. I took 3 tests different days but all say negative ? 
Now my pass I was pregnant but lost my twins in a miscarriage, and before that my periods was irregular but now since then my periods been around 27-29days. Also only today I've been having  very sharp pains in my clit and lower belly (sorry bit detail) 
So my question is should I was till end month to take another test ? Or should I get a blood test ? /: