Thumb suckers?

This is so embarrassing and my least favorite feature about myself. I am 23 years old and I still suck my thumb daily. I can't stop. I've had braces since I was 10 and still have them on. I haven't been to a dentist in 4 years because I am so ashamed of myself and the poor decisions I made as a teen regarding my dental health. My parents always worked so there was no one to FORCE me to go to my ortho appts so I just stopped going an then we move and I never found a new one. My question is, does any one else suck their thumb? How have you managed to stop? I have a 2 year old and I am so scared for her to start school because I hate interacting with people. My mouth is so ugly and I feel like people always stare at my mouth :( i have a severe underbite so it looks like I don't have top teeth :(