Like others mentioned, the form was bad dude. I'd deduct 20 of them just off the form, not to mention the momentum.
As far as how many 'I' can do?
Too tired and lazy at the moment, I'll try them at a later date tho, I can probably do around 40 ish.
how do i fix my form? im in a natural comfortable position with my back straight and hips up touching the floor with my chest and im locking out in every rep, ill do 50 with my legs on top of a chair with my leg in the air next time
The swinging motion you did just makes it easier is all. It'll be more difficult if your back is straight, you slow down the pace, and move in a more controlled manner. Still very impressive though, no one is denying you that.