Late/ birth control

an

I’m 17, never missed a period before. Is sexually active.

I was late 14 days! I again have never been late EVER in my life and I took a test at 14 days late and it was negative!

Today is 15 days late and my period came! So how do I tell my mother I want to be on birth control?? I want to be on birth control to fluctuate my periods and keep from getting pregnant (we do wear protection) but to be extra safe.