A 5th always leads to a 6th, 7th and 8th. Okay, I know that was bad but you really don't need a drink. I'm sorry your dad isn't supportive and he's cutting you down.
You think that you know what your problems are and that a psychologist would be useless but you are also telling us that "I don't know how to change my life." A psychologist can help you identify what you need in order to make that change. Consider them a life coach as opposed to a fixer at this point. What harm could it do? Rather than shoot down the idea, give it a try.
I wouldn't worry about having a girlfriend at this point. Romantic relationships when you aren't healthy or feeling good about yourself are only a bandage to the underlying problem.
Take care of yourself first.