Sorry to hear about what you're going through. It must be really tough to deal with one parent who's alcoholic, while the other is so far away - I'm beginning to understand why you feel so alone.
Feeling alone amongst a crowd of people is more common than you'd think. Many people report feeling alone in a large group of people due to the less attentive, intimate interaction with others. Some people also feel this when the group of people they are with doesn't feel like the right fit for them. As a personal example, I feel alone when surrounded by a crowd of rowdy teens drinking, because it's not something I do myself, enjoy or even agree with - thus, I don't feel that sense of belonging, and so I feel alone.
Being open is really difficult, especially with people you don't know well. It seems like there is a link between struggling to be open, and struggling to make close friends. The reason is that closer friendships require being open and vulnerable. Obviously, you don't want to be telling someone everything straight away. It can easily start with not responding to the question, "How are you?", with "I'm fine" if you're not feeling good. If you're not feeling good when someone asks you, don't be afraid to talk about how you feel. That's the starting block for building closer relationshipsx
Much love <3