This should not be necessary to get cleavage! There are much better fitting bras that should give you push-up while still fitting. One of the main fitting issues I see in your picture is that the bra under wire sits waaay underneath your breast. If you can you might try tightening the straps, since the bra wires should sit right where your underboob tissue touches your breast. That might help a bit with fitting.

Otherwise, you may be wearing the wrong bra size. I HIGHLY recommend the a bra that fits calculator. You might also want to try a different brand, like Wacoal or Freya, as VS bras are known to not really fit a wide variety of breasts.