I am not sure if you can rescue the panorama above in Photoshop; manual work is problematic since Photoshop transforms the images to fit a chosen "layout".
(An aside - it seems your horizon is not level, and normally this is crucial for these types of panos; your stand and head must be properly leveled. If you try to correct this in Photoshop the height of your pano will very small indeed.)
I have used Photoshop for stitching panoramas earlier - with up to nine images and have sold copies of the panoramas. But I suddenly ran into problems in Photoshop without being able to really identify why.
I shoot with a Manfrotto 303 SPH head to ensure good alignment, and also to adjust for nodal point. I shoot both landscapes and architecture.
My experience is as follows:
Use good overlap between the images, at least 25% (I normally use 30%) with lots of extra room on either side and above/below the panorama you wish to cut down to (again 25% is a good measure).
Ensure there is some clearly identifiable structure in each of the images that overlap, this helps Photoshop to identify where the merging can be done.
Sometimes Photoshop just cannot seem to figure things out even if great care is taken.
As far as I can tell there is no good way to solve this in Photoshop. I had my first issues with Photoshop about two months ago, having spent a weekend walking and shooting landscapes. Photoshop would not handle any of them.
I ended up downloading Autopano from Kolor and it handled all of the panoramas, so I ended up buying the program.
My workflow now is:
Batch process all images in Adobe RAW (manually setting white balance, noise reduction, exposure compensation, highlight and shadow compensation etc., the same for all files), save the resulting files as TIF.
Import into Autopano, and adjust the panorama; crop and render to Photoshop format.
Open in Photoshop and do further editing and printing there.
To be able to handle the panoramas (in reasonable time) I upgraded my PC with a new motherboard, CPU and RAM.
I have two SSDs (one for OS and programs and one for images and Photoshop scratch disk), 32 GB RAM and an i5 6500 CPU running at 3,2 GHz. I still on occasion run out of memory if I have Autopano and Photoshop open at the same time.