Hi Loubel, I am another one who had an immediate LD recon and loves it. Diagnosed August 2010, I had chemo first as my tumour was massive and aggressive, then LD recon (without an implant) Feb 2011 and 25 rads Apr/May 2011. Like yourself and DJ, my scars tighten in cold or damp weather, and like you I live in Scotland (west central) so that has been noticeable the last couple of weeks.
I have not experienced the 'touch the front, feel it in the back' effect, though was aware this can happen. I more find that sometimes I do something and feel it in my boob/chest where the muscle has presumably been stitched in place, suggesting my LD muscle has not yet quite forgotten it was once part of my back!! Swimming and walking with pole both give me a stiff boob!!! I still do some stretches daily and have been told to do them 'for life'
I asked about recurrence at one of my check-ups and was told it was rare, and as DJ has said, most likely to be on the scar or at the tumour site. I was lucky (?) in that my tumour was slap bang in the middle and front, so chest wall recurrence is very unlikely. When pressed, they said if it did recur, then they may have to sacrifice the recon, depending on where and how large, but that another one (presumably with an implant) would be possible afterwards...! Hopefully I'll never have to find out.
Hope the u/s goes well and this is soon all behind you.