Hello
I think that things will get better for you.
What you should remember is that your father is a drug addict, and some of the things he says he doesn't mean. There's a chance that he's emotionally abusive , and if he makes you feel bad about yourself, then he is sort of emotionally abusive in a way. Thus, it's better if you just ignore a lot of the shit he says because he just does that in a tough parenting way, but when it's "Drunk/high " tough parenting, then some of the things he says are going to be very mean or bad. But not everyone is going to be like this. There are people who are nice and loving. These people won't abuse you .. rather they'll take care of you, and nurture your feelings. It's okay to talk about your feelings. Your father probably wants you to be like him because he can't be hurt, but at the same time.. you hurt yourself on the inside by keeping all of these emotions within yourself. But where's the point in that? By sharing emotions and experiences with other people, you grow as a human being. And that's what counts.
Perhaps it'll be better for you if you slowly but surely replace smoking pot /weed/drinking with some other activity that puts you into social situations. I know that using those substances as a crutch to assist might help at times, but it's better to just mix around, and slowly come out of your shell, because that'll really help you feel better about yourself, and there's no better feeling . Also, I think that you'll be able to do it because you want to improve, and you certainly showed it by telling us these experiences/thoughts of yours.
As for your sex life, I think that semi-open relationships can be fun. But you can be assured that when it comes to dick size or pleasuring a woman, sometimes women just wanna be loved, and that when they do it with someone who loves them and is loved by them in return, it feels so good and sensual. I think that's a bigger factor, and that you've everything you need to pleasure and satisfy your girl . Most of all, when you do it, be confident and remember that you can do whatever you like as long as she's okay with it. Who knows.. this girl might actually want to fulfill your sensual desires too.. wild, unrestrained sex is usually the best sex of all.
I'm sure that you'll be able to overcome this period of self-doubt. All you need is self-belief and a strong sense of your self-worth. " I can do this " should be replaced with " This is nothing before me. " Think of everything this way, and you'll be going places. Better, happier places.
Stay safe and remember that you got us too! We'll always be around to support you, assist you and make things better for you.