I’m going to assume this was originally written by someone who speaks (informal) UK English.
The dorm’s fire alarm went off in the middle of the night, and now we’re awkwardly standing outside in out PJs.
It’s a compound sentence; I’ve already mentioned commas in compound sentences a few times.
We’re stood isn’t standard for either UK or US English. Unless your intent is to imitate the speech patterns of someone with less-than-stellar grammar, I recommend against it. (We’re stood actually means that someone or something not yourself is standing you there; you’re the object of the action, not the subject doing it. And it’s still awkward and clunky.)
Apostrophes do not make plurals. Even if it’s a plural of an acronym (in which case you ought to, y’know, capitalize the letters of the acronym itself), do not use an apostrophe before the s (except in the uncommon instance where it would form an actual word without the apostrophe: multiples of A would be A’s, whereas multiples of B would be Bs). Or, in the example sentence, you could just say pajamas and avoid the issue altogether.