Head shape looks different in self shot with iphone and mirror shot?

So when i take a picture of myself i look fine i look the way i look when i look in the mirror but when i take a picture of myself with my iphone at armlengt i look different my while face shape changes it is very weird in the mirror shot my head looks a bit more wijde and in armlengt selfshot it looks very long so which one is more Accurate shape of my head

You look bad in photos because you are not using the camera correctly. If you hold the camera out at arm's length and take a photo, the lens will have to be at a wide angle view. This distorts your face. Also, any time you have tha flash blasting off in your face, it is going to make you look awful.

To get a decent photo of yourself, the camera needs to be mounted on a tripod, you need to be in good, natural light, (NOT directly under sunlight), the camera lens needs to be at a medium telephoto length, and the self timer used to activate the shutter. Can all that be accomplished with a phone? NO.