Can seem to load a sharper image

I’m using ghost on their own hosting site

my issue is I know the largest size image I can upload due to my website’s code is 1675…I resized the image in PS and used the jpeg mini software and the image still looks blurry

…now this image was taken on the 35mm compared to a lot of my shots which were taken on a 85mm

if you go here

and you find the image and click on the little arrows in the corner of the image it loads a sharper iamge. any thoughts on what I’m doing wrong.

ps I have tried 5mb to 15mb sized images no luck