There’s a boy on my mind and he knows
I’m thinking of him
On my way through the day and the night
The stars shine above me
He’s been gone for some time but I know
I truly love him
And I’m singing a song
Hoping he’ll be back when he hears it-----@

If your love’s gone away just like mine
You’ll feel like crying
Sing along maybe once maybe twice
Let’s try it together
Some sweet day no one knows you’ll return
And you’ll be happy-----1
Shout it sweet in a song
Listen to your heart it is singing-----2

Questions:
(1) Can we interpret it like this or do you have any better ways?
You'll return on some sweet day that no one knows and you'll be happy.

2) I guess this line should have been "Listen to your heart singing." The songwriter put it this way because s/he wanted it to have the same number of syllables as "Hoping he'll be back when he hears it"(9 syllables), because both lines have the same melody. What do you think?

Please explain in detail! Thank you!

(1) You feel sad now, but one day you will be happy again, just let go the blues away and follow the heart.

(2) both for the syllables and for the meaning: it has a slight acceptation of "pay attention now and you will see that your heart does not want to be in the blue"