The little can also mean; insignificant or unimportant in this situation. Meaning that they can be saying, I am not worthy or i did not know that I was this important! Happy Learning!

No, it's not about age. the expression means "just me".

It's not about age, or size.... itls kind of like "小小的我 ". "old" when it comes before something is like 老 in chinese, "Good old bob" = "my good friend bob"