I think you've done a good job on pp'ing this picture with GIMP, I've used GIMP, with Linux, for decades now and love it. I would like to see, by way of comparison, a version with the sky cropped down a little, say to the darker part of the cloud on the left.

A long exposure has given just a enough movement in the sky to create a very subtle photograph. :)

Whether this was posed or spontaneous, the shape of the young lady's pose is a classic 'S' and you released the shutter at just the right moment. I congratulate you as I struggle with people pictures at times; so appreciate your work here very much. :)

Good the framing is just right, retaining the grasses at the foot, holding the edge at a natural finish, the composition is good with the tree placed just-so and the exposure saturation is very pleasing too. Regards, Ian.