The tenses are a bit confusing. "Whenever I needed you I found you always stood by my side, and that trait of yours really meant a lot to me." I added the comma just to create a mental pause for understanding. Also, I removed "have" because I don't think it's necessary and it changes from the past tense, which is a bit confusing. Finally, I changed "thing" to "trait" and corrected "your" with the proper possessive pronoun "yours" for that situation.