My attitude since I'm a very young person is...

This is simply not a correct grammatical construction. "Since I was a very young person, my attitude has been..." is correct. Of course, I don't mind if you use this cute little colloquialism, which I believe you got from your Yiddish-speaking family or neighbors. It's cute but please dont' say you "have a good ear for good language" thanks to learning four other languages. None of them have (yes, "have", because this "none" is plural) taught you to correct this mistaken construction.