I hate tattling. When you and your siblings were little, I helped you to not tattle by teaching a few rules that apply to young (and old) adults, too.
1. Big harm. If your 4 year old brother is about to jump off the patio roof expecting to fly in his Spiderman pajamas - TELL (an adult) because he could get badly hurt.
2. Big damage. If your 6 year old brother is lighting a plastic cup on fire in the garage - TELL (an adult) because fire spreads quickly and could burn down the house.
3. Concerned. If there is no immediate harm or damage but you are concerned - TELL the person involved. "I'm concerned about you. This could really hurt you or someone else, or cause costly damage. Please stop and go tell (an adult who can help.) Or I will."
4. Trying to get someone in trouble. If there is no immediate or pending big harm or damage - DON'T TELL because that is tattling, trying to make yourself look good or build yourself up at another's expense.
Drunk driving? TELL (someone who can help) because there is a big risk of physical injury and death to self and other as well as costly damage and legal consequences. Teammate is late for practice? DON'T TELL (unless coach asks) because there is no immediate concern.
I love your efforts to tell and not tell, well.