You say U = ck^2 and k = m

so U = cm^2

so substituting k and U into your equation
(substitutions in [brackets])

E = (U/k)c
E = ([cm^2]/[m])c
and simplifying
E = ([c^2 m^2]/[m])
dividing and rearranging terms
E = c^2 m
or
E = mc^2.

Which is the Einstein equation. You've done nothing, we're right back where we started.

This formula explains nothing and proves nothing. You've defined some spurious variables in terms of others so that when substituted and multiplied out they yield the same equation anyway, no matter what value you arbitrarily assign to c. In other words, you've rigged u and k to get the answer you want. And all this talk of the densities of space, Higgs fields, accelerating photons, and the two infinities are just gibberish.

And density, by the way, is just mass divided by volume. A ton of lead weighs exactly the same as a ton of feathers. "Something that forms the density within that space" is meaningless. Those words do not refer to anything in the real world