You lose the bar behind you because it swing outwards in a pendulum fashion. This means that it's not coming straight up to you, it's coming up and back IN TOWARDS YOU, which means it is causing you to miss because the bar is tracing a semi circle, up, away, back towards you. This is exactly what I was just talking about with the S curve being exaggerated and creating problems: it's a primary symptom.
If you look at Dimas the bar does NOT go out front. The bar path is very much mostly straight up--he is exploding but doing it properly. Certain other lifters don't even arch that much--many of the Russian greats don't arch back much at all, but they get a very straight bar path.
The key is straight bar path--arch or no arch you still have to have it.
Yes you are a bit slow under the bar. Yes, you are jumping too much. The goal is not the jump--you don't even have to get all the way on your toes, as proven by some of the elite (although most do)--the goal is explosion. You might be slow under the bar because you are trying to milk the explosion for more power, but it won't work because the bar is already moving--you're losing time to get under the bar. You get one shot to power the bar up--after that any more pulling on it won't help it will only slow your progress down because you won't be down in time to receive.
Right now your explosion is fine, you're just trying to get more and more out of it when you can't. Spending all that time in the air makes your explosion feel much more sluggish than it is.
So: straighter bar path, and make ONE decisive fast pull and then get under...don't try to milk more out of it by jumping or staying up there.