What a lovely space. It doesn't look off centered. You actually have to standing in front of the fireplace to notice it. I'd keep the mantle.

Hi, Sandy--

Truthfully, the mantle does look well done, and I'm guessing the wall was framed out this way to offer a spot for fireplace tools to live either on the wall (pre-millwork) or on the hearth nearby to avoid a mess - thanks, helpful builders! Since you're not using the fireplace as such, it's totally fine to do as you are and place other items nearby. It really doesn't draw my eye, since so much of your decor is uniformly light and bright - in truth, the eye spends less time wherever there's less detail.

Accordingly, I'd consider moving that basket away and doing a flat, single-panel fireplace screen in black for an even sleeker look than your current option so the eye keeps moving and lands on your bigger focal points above and elsewhere. Cheers!

Your fireplace is fine, in fact the room is fine. Don't screw it up. Don't bother with the stone.

I think the contrast between the classic FP surround and the contemporary shelves on the right is more of an issue. I'm not a fan of big box store decor, so the items you are decorating with aren't to my taste, but what probably makes it "off" to you is the fact that the coffee table isn't lined up with the firebox opening and the sofa is partially in front of the opening. You might sense better balance if you flank the FP with the two chairs and place the sofa where you have the floor mirror, centering it and the coffee table with the firebox. If you remove the shelves, you could try the floor mirror on that wall instead. You don't have much walk space around the sofa right now. The chairs might do well on that side, leaving the step down entrance clear. I'd rather leave the space in front of the step clear of furniture.

Very pretty room. Maybe a little too much going on? I'd prob remove the candles in the fp and add some books to your shelves. I would love a beautiful contemporary art piece in lieu of the mirror or frame that you have on the mantel, but I would take my time finding it. I would also remove the piece by the fp with the tray.