Autumn

Hello there, bonnie babe! Decent little poem you've got here, let's take a look, shall we?

If only I were young,
I'd try my best to catch them.
I suppose I will make do
With dreaming of my youth.

I happen to like this stanza. It would be really cool if you changed the last two lines to an image of chasing after the lost years of the persona's youth. You know, trying to catch them as one catches leaves. They're dead and gone, but there's also the hope of new leaves in spring. I dunno, just a thought.

Before I knew the love,
And loss that this life can bring.

You don't need a comma after "love". You do, however, need one after "birds" in the third line of the last stanza.

Hmm, "autumned body", huh? There are several real words you could use instead, like "withered", or "exhausted" if you're trying to say that the persona's body is worn out. Just thumb through a thesaurus, they're the best. But don't get carried away: use only the word that fits and not something extravagant or grandiose.
C.S. Lewis put it very well:

"Don't use words too big for the subject. Don't say 'infinitely' when you mean 'very'; otherwise you'll have no word left when you want to talk about something really infinite."

And with that gem of wisdom, I take my leave. It's a nice little poem, so good work. Simple but sweet.

Happy scribbling!

Sincerely,
Rose