I like it the way it is. I'd move the R a few inches to the right...maybe even slightly behind the vase

I think a piece of art instead of a mirror. The mirror is not reflecting anything interesting (the globe of the ceiling fixture) and the frame is too dark and too big. I cannot see what else is in the room, but a print that picks up an accent color in your furniture, pillows or rug would be better. The size of the mirror is good so pick a picture the same size and then decide what to keep on mantle. I would guess that the orchids on each side would be plenty. Look for a tall vase in coordinating colors for one side of the FP on the hearth.

Pier 1

I'd get rid of the vases and use some larger pieces instead. Also layer (overlap) things a bit. [https://www.houzz.com/photos/spring-mantle-phvw-vp~133669[(https://www.houzz.com/photos/spring-mantle-phvw-vp~133669)

I like your mirror but think it is a bit low. Try 8 1- 10 inches from mantle to bottom of mirror.

Keep the R on the left as suggested above or keep the honey colored vases and put them on each side of the mantle centered on the pilasters which are the vertical supports of the fireplace. Get rid of the rest