I never called myself a "junior" engineer, even at the beginning of my career, that is lowballing yourself at best. You are an engineer with 6 moths or one year, etc... of experience. You need to sell yourself to employers, clients, etc... no one will advocate for your success or a fair compensation. If you are really unexperienced, let the interviewer to assess that fact. No need to lie on your resume or interviews, just don't put yourself in a position where recruiters/hiring managers will have very easy to give you a worst compensation for the same work you would otherwise do at a better rate.