Hi Stephen - As someone who has struggled with this same issue quite recently maybe this will help -
I have used Google 'Picasa' for many years finding it easy to upload, keep track of images and post into the text box with ease.
Picasa was recently replaced with 'Google Photos' and immediately caused me difficulties. However, despite the initial problems I experienced when it first changed over coupled with Win10 it has proved just as easy to upload (if not actually easier) from images stored in the 'My Pictures' folders on the PC. Once in 'Google Photo's', the storage is also very easy to search with quick access to any folder. One right click on an image within gives a drop down menu and one click is all that is needed to take that image address and insert it into the text-box on here.
The only real difference I have found is the number of lines of text for each image - irritating and a nuisance to begin with, now totally unnoticed - posting images within the text really is as easy as before.
I can only say - if I find it easy then it really must be as usually I do struggle with such matters. On top of that it's basically free

(You'd need a truly huge file before any charges begin)
Hope that's of use - Tug
I have just tried it to count the clicks required-
one LH click to open the desktop
another to open 'Albums'
one more to open the desired 'Album'
(once this is done there is no further need until the album is closed so only four clicks required for each image onward)
one LH to open the image
One RH click on the image to open menu
One LH for 'copy image address'
One RH to paste into the bkts in the text box

I now find it all pretty straightforward so if I can be of any further help just ask
Regards - Tug