I genuienly don't believe you.

Either you are mistaken, or you likely have some kind of genuinely concerning medical condition.

Like I'm not trying to dox you, but take a picture of yourself, wearing fairly tight clothes, in the same pose as the anime figure, line them up at the shoulders, and overlay them and compare the outlines.

Use a camera that is further away but also zoomed in a good amount, and if you do actually want to post the image, blur out your face and any tattoos or scars... totally fine if you want to just keep such an image to yourself.

What you will likely find is that you are mistaken, you misjudged the proportions, or perhaps you are a skinnier lankier dude, but not literally the same limb thicknesses as the anime figure, or, perhaps you actually are that skinny, in which case, if you are past puberty, you likely have a relatively rare medical condition like chrones or muscular dystrophy, or anorexia, or are malnourished.