Asking for a raise

Ive worked at a fast-casual restaurant for over 7 years, i am one of 2 shift leaders, and am one of the highest paid employees. I work my ass off, cover shifts when needed, never call out or switch shifts, havent left and come back at all, and have grown tremendously as an employee and as a person. I have not gotten a raise in probably almost 2 years, and its been brought up to me by every other employee recently that theyve been given raises. The only person who is making more than me (other than the manager) has been there less time than me, can only work 3 days a week, has been out for months at a time due to health/legal issues, and doesnt have some of the responsibilities that i have because of his schedule. My problem is any time i work up the courange to ask about a raise i make a mistake or someone sats something that shakes me. Recently ive been dealing with a new employee who tells me all the time that he should have a higher position/ make more money than me because hes worked in food service for longer, even though it was an incredibly different job. My confidence has always been an issue and i need advice on keeping my head up and asking for what i deserve, help!