Unless your degree is in English or education, you cannot call yourself a teacher.

Nobody should be teaching without the relevant qualifications. A relevant degree and a classroom based TEFL or CELTA qualification. Otherwise you're just a native speaker using your students to get passport stamps. You also leave yourself wide open to unscrupulous recruiters or schools who can exploit your niavitiy about teaching standards and methodology to thier own ends.

Not to mention it's not fair to your students to receive education from someone who doesn't know what they're doing!