A unexpectantly came out

Unexpectedly  (which half?)

she screamed, embarassed.  (it's like "sleepily")
(Did you mean to describe her scream, or her state of mind?)  Wouldn't she be surprised first and embarassed second?  That is, it would be a surprised scream rather than an embarassed scream, which I imagine as more like a squeal.

Small logic problem??  A&B  + C&D (we) arrived together at the room.   (Or did C&D just happen to pop in as A was pulling B into the bathroom?)  Anyway, B had to know you were there at some point in time.  Did she just forget about you, or assume you had left?  But either way, "unexpectedly" seems strange, since the action is all focused on A&B.  The unexpectedness belongs to C&D.  Or was it unexpected to A?  How about "abruptly"?  OR,  "To our great surprise and delight,"?

Shouldn't it be, "straightened up facing us"? (You said she bent over, not that she was kneeling.)

Whom was she facing when she bent over?  At some time she must have turned around to face you.  (If you're going to describe details, you should think it through and get them right.  -   I know this is a difficult scene to picture.)

New2grammar

she embarassedly screamed.

  Dagnabbit, New2, you guys are such great spellers, I assumed I was wrong about another of my famous double consonants!  I even started wondering about "occurrence" and looked it up.  Okay, two sets of doubles.  Why not look up "embarrassed" while I'm at it?  Hmmm.   Two sets of doubles, the way I've always done it   -   until this thread!   -  A.

Don't get him started!   (That's a joke, Yoong.)

New2grammar

Avangi

Did you mean to describe her scream,

 Yes. Is it not a natural thing to do?

The point I wanted to make is that there are different varieties of screams.  Some are involuntary   -   an immediate response to a frightening surprise.  ("I thought I was safe and alone": SCREAM).  Some are affectations, requiring some thought.  (Gee, they're looking at me naked.  How embarrassing.": SQUEEL).  The way your story line evolved, I would have expected a scream of the first variety, but you seemed to be trying to describe one of the second variety  -   an embarrassed scream, not a frightened scream.  I was curious as to what your intention really was.

  -A.

Edit.  My remark, "It's like sleepily" was meant to evoke the adv. or adj. discussion of an earlier thread (sleepily I walked  or  sleepy, I walked).  I wanted to point out that the same useage could follow, as well as precede the action.  (She screamed embarrassedly  or  She screamed, embarrassed.)