Pregnant??

Stephanie • I`m 30 years old been trying almost 13 years to get pregnant. I have a 14 year old son. I don`t understand why I haven`t got pregnant at all!! I tried for 15 years and I finally got my baby girl April 25 2017
I had my period 01/9/2016 _01/13/2016 then 02/10/2016_ 02/14/2016 then last month was 03/10/2016_ 03/14/2016 I took a test last Thursday it was negative?? How long before I should wait to take another one??