Suspect that AFMA and perhaps using a tripod will help. One easy way to field test is to use live view to focus on a target. Turn off live view and focus on subject. If the distance scale shifts then you have a problem and know which direction to adjust.
You 'blew the image up'. If this involved resizing the image what settings were used in what software? This could seriously affect things.
Were the images printed? Were they sharpened sufficiently for the media in use? What was the PPI count? Different textures and finishes do want different treatments.
Just a few other items to consider in the workflow where softness can creep in.