I love it. wouldn't change any content, but there are some grammatical errors that could use fixing

since reaching the last settlement, the safe havens amongst the sands.

improper plural modification of singular "settlement" could use "one of the safe havens amongst the sands"

as she did hers

should probably say "as she did hers to him"

I was confused about this statement - for whom was it difficult?

but it was unnatural and required a fair amount of effort in its own right,

I think you might want to put "unnatural for her" to clarify

the sand covering your mouth and filling your nose,

this is the only place you use the second person "you" and it feels out of place to me. should be her

Last paragraph (love the last line) has a few sentence fragments, but it works for me as is.

Great story!!!