As previously stated, what you’re describing are mainly self-esteem and self-image issues, which is why I still recommend the book I mentioned earlier (
Psycho-Cybernetics). It goes deeper than surface-level motivation and helps you understand how your self-image affects your behavior, confidence, and the way others perceive you. Many of your concerns such as respect, achievements, anxiety about the future, and success with women are connected to this and can improve once you start fixing your reality, or in manosphere terms, your "frame".
Also, you are in your prime time to work on your appearance, status, money, and personality. At 18, your responsibilities are minimal, which gives you a huge advantage if you use it correctly: lifting weights, improving your style and grooming, socializing, working extra hours, reading, and applying what you learn. Looks can also be improved over time through working out and, later on, things like braces or cosmetic surgery once you’re making money. If you stay consistent for the next six months and go “monk mode,” it’s very realistic that you’ll be a completely different person.
However, I wouldn’t completely cut off socializing. Your social network tends to shrink as you get older, and many older men try to compensate for this later with little success, and you will have less opportunity to practice. I am sure
@Manure Spherian can explain this better than I can.