Hi There, I'm Kelli I'm 22 Years Old Have Two

Hi there, I'm kelli I'm 22 years old have two children already, i am on the implanon and im worried I could be pregnant. As I've been getting the following symptoms;
Nausea
Abdominal pain
Headaches
Going to the toilet more often
Feel really bloated and feel as if my clothes are getting tighter
White discharge