Как можно

[Marga 1]

КАК МОЖНО это написать?

Но мужественно пыталась сделать спокойное ( скорее невозмутимое) выражение лица, не знаю насколько это получилось.

[yelena.t]

But she was bravely [making an attempt]/[trying] to straighten her face and look calm :)

[_03]

I was trying to put on a calm (or I would rather say deadpan) expression. But I dunno whether I had succeeded in it/whether it had produced the desired/intended effect

[PERPETRATOR™]

I bravely tried to look calm. I don't know what the result was.

[yelena.t]

упс, хвостик упустила
+ I was bravely [making an attempt]/[trying] to straighten my face and look calm. I'm not sure I quite succeeded.