Method partial hanging - slipknot moving when i put my weight on it?

[sweetbraid]

i'm certain ive done the knots correctly but when i try to put my weight onto the slipknot, it starts to loosen. should i use a different knot? what am i doing incorrectly?

i dont have a place to tie the rope from except a doorknob in my bedroom, around my hip height. ive seen some videos of people tying the rope to a higher spot - which i dont have access to. the metal bar in my closet is not strong enough to hold my weight and i have no other places to tie it from.

thanks <3