[Grammar] A little help with this sentence, please.

[Sammy_]

Here is the sentence: Once, she had been leaning over the balcony of her room, trying to see what was making an odd sound, when she fell over the side and found that it was nothing more than a bird.

Since "trying to see what was making an odd sound" is set off by two commas, doesn't this mean that it's added information? If so, then shouldn't there be a comma before "and found that it was nothing more than a bird?" Because if you take out "trying to see what was making an odd sound", the sentence wouldn't make any sense. Also, please tag and explain any grammatical errors within this text.

Thanks,
Sam

[Camán]

(not a teacher, just a simple writer)

I think you can skip both the first and second comma to bind the sentence together and to make use of the third one.

If I might be so bold, I would also change the first part a wee bit and end the sentence,
baring in mind that the sentence is taken out of its context, like this:
Once she was leaning over the balcony outside of her room, trying to see what was making that odd sound, when she fell over the balustrad and found it to be nothing more than a bird.

If you wont kill me, might I also play with the sentence to follow?

Subsequently she found the ground under it to be firm and dry and her local GP to be a man of upright character with a well-documented believe in patient confidentiality.

Camán

(if you not from the British Isles: GP=General practitioner)

P.S. Hello admin.
I've been a bad boy, a bad boy.
Wont do that again.

[David L.]

Once, she had been leaning over the balcony of her room, trying to see what was making an odd sound, when she fell over...

Firstly, the commas are very important.

Is it necessary to be so specific about 'of her room'. We need to fix up 'leaning over the balcony', and with 'of her room', the sentence would become long-winded and cumbersome.

Secondly, "...when she fell over the side and found that it was nothing more than a bird."
On first reading, the poor reader thinks you are referring back to 'side' when you next write 'to find it (was nothing...)'!

Altogether, how about:
Once, she had been leaning over a/the balcony railing, trying to see what was making an odd sound, when she fell over the side, only then to find that it was nothing more than a bird.