I read about you can develop sepsis from bitting nails, extremely worried now about that. what are the chances? is it really possible?

That's silly: Bacteremia -- probably. You get bacteremia when you brush your teeth hard or pass stool. Sepsis (i.e., immediately life-threatening bacteremia)? That's deadly -- I've never seen this either clinically or as a pathologist, no pathology textbook lists this as a mechanism of death / unexplained sepsis. Nail-chewing is genetic. Use clippers every morning, tell folks you like them kept very short.

Very slim: Although anything is possible, it would be exceedingly unlikely that you would develop a blood infection in this way if you are otherwise healthy.

Biting nails : you need to have broken skin and have an Immune problem or a serious skin infection to get sepsis from nail biting

You'd have : Bite your nails so significantly that you compromise the associated nailed to create a portal of entry for bacteria. This would be exceptionally rare but not impossible like a person getting sick from flesh eating bacteria after a paper cut. I'm not sure anyone can quote you reasonable statistics due to its rarity.