You are putting the bar a little too close to your shins. This results in your shoulders being too far forward of the bar. Drop your butt slightly. Drag the bar all the way up the legs.
Yes, you are.Am I squeezing my chest up enough?
They look fine to me, but you could answer this question yourself with a tape measure and an Internet search engine.and are these are bumper plates I am using...are the official diameter of what would be used in olympics/ in an SS gym in America?
Make the corrections above and keep adding weight.