Congrats for giving this lift a try. Without coaching and with the limitations you mention, you're doing ok.
Now, some advice.
1)Make sure your grip width is correct, which means that it should be wide enough that when the bar is hanging, it crosses your pubic bone.
2)Try to get some regulation sized bumper or tech. plates. Doing the snatch from a low starting position is hard enough for experienced lifters, nevermind someone trying to learn technique.
3)Back should be straight.
4)Shoulders should be directly over the bar, which should be directly over the base of the big toe, at the starting position (Set)
5)The bar should start from the floor and move towards you, not away, which is what you're doing now.
6)Think of extending your knees by driving them to the rear and sweeping the bar towards you as you rise. Think about staying flat-footed through most of the pull.
7) The movement to accelerate the bar should be thought of as more of an explosive catapulting motion from the hips, rather than a jumping motion of the legs.
8)Don't think of shrugging up but, only shrugging and pulling yourself downward to get under the bar to the catch position.
Good luck. And, keep posting and asking questions.