Hey Milan,
I think you did and excellent job isolating this against the BG. The diagonal comp works very well also. The light is a bit harsh......so you lost the details in the whites of the flowers. A diffuser would have helped in this situation and allowed you to gain more detail in those whites by taming the light. The most effective and inexpensive tool we can have in our bag!
Hi Milan. Good suggestions by Roman. I agree that the diagonal comp and the separation of the subject from the background are strong points. I would suggest a round of nr on the background to smooth it out more - it looks a bit gritty on my monitor.