I Keep Biting The Sides Of My Tongue And The

I keep biting the sides of my tongue and the sides of my mouth and it gets so bad that they bleed heavily. my dentist says I have a size or schedule(I cant remember what she called it) 4 overbite and size or schedule 5 something else I don't know if this indicates I need braces or if its not enough of messed up teeth to have braces. I sucked on my thumb for 10 years of my life also.