I do tons of panos. One thing that works for me is to use the camera in portrait orientation, and generally focal lengths of 45mm or longer. This avoids that distortion at the left side of your pano, where the trees were obviously much closer than the rest of the scene.

Also shoot this with manual exposure - auto exposure modes may cause irregularities in brightness from one panel to the next. You should have a consistent exposure whenever possible.

If you find that Lightroom/Photoshop and other similar programs fall short of your expectations, try PanoTools GUI. It is an industrial strength stitching program with lots of control.

Here are some panos that illustrate what I am suggesting:

_DSC1933-NIKON D800-3064517-(25-10-17)-Pano by Gene Lugo, on Flickr

_DSC2196-NIKON D800-3064517-(03-11-17)-Pano-Edit by Gene Lugo, on Flickr

_DSC9742-Pano by Gene Lugo, on Flickr

_DSC5457-Pano-Edit-Edit by Gene Lugo, on Flickr