"I've always liked the rain, it helps me sleep." said the boy, while staring out the window as it poured down with rain. "When I was your age, I used to hate the rain. My mother wouldn't allow me to play outside when it did," saying, whilst I close my eyes and tilt my up towards the ceiling. "Now I find it the most calming thing there is to listen to..."

I've always liked the sound of the rain, it helps me to sleep.
Peering out of the window- Staring sounds too intense
'said the boy, peering out the window upon the dreary downpour. Joining him, I said:'
"When I was your age, I used to hate the rain. My mother wouldn't allow me to play outside when it did,"
Looking up towards the ceiling, I said:
"Now, I find it the most calming thing there that there is to listen to..."

I didn't fix the tensing here I had overlooked that.

Here are a few suggestions for cleaning up the final paragraph... They may not be fully correct, however I found it really difficult to read and this is how I would probably word it.