If I may have a differing opinion, the last image seems to me to have captured everything that you value in your mother, a lovely lady with a beautiful child treasuring that moment in her life. While the picture is high-key, it doesn't look bleached out to me (but I do have my monitor brightness set low). I feel that adding a different sky is not needed. The background is not quite blown out - I see some shading quite high up on the right hand side and the horizon.
FWIW, I quite like the image as is, it has a nice dreamy quality to me, however, not having known your mother, it is of course, subjective, and may not be representative of your vision of your mother. Assuming little detail is lost in the printing, and printed at a slightly smaller size, i.e., 18 x 20 or something like that,this would be a picture I'd love to hang on the wall.
Regards,
Chris.