thanks all of you. will definitely give these some thought

When my guitar(s) don't have fret markers, I use a little blob of whiteout. It doesn't hurt the finish and is easily removed/renewed.

Hi Alex, several of my incoming students have complained to me about neck issues. In most of their cases the culprit seems to be the fact that they insist on actually looking at the fretboard which involves an streaching of the neck so as to see the fretboard. We don't need to see the actual fretboard of the guitar; it suffices to look at the neck of the guitar from the back of it and only see the edges of the frets at the 6th string. Once you realize where the fret markers are, there should be no need to actually look at the fretboard itself. Would you try this and see what changes over the next week or so. Keep up the good work. You are doing really well.

For posture I tend to use a Guitarlift (https://guitarlift.de/) as it lends itself to you helping you sit more naturally than using a footstool....other footstool alternative supports seem to do the same job as part of their design.

With regards left hand looking try playing some easier pieces and learning easier pieces where you don't have to look at you left hand....maybe focus on sight-reading the piece without looking too much at you left hand and an old favourite..plonk yourself in front of a mirror (or reflection from a glass door)...you can check so much out doing this, posture, hand and fret positions etc....hope this helps a little....oh and as Tavi always says take breaks and release any tension.