Never been in a relationship 😢

I'm 17 and I've never been in a relationship. I feel like I'm missing out on such an important life milestone and I really want to have somebody. I graduate high school in a few months and I want to have this experience before I graduate. What makes it even harder is that I'm super shy and don't know how to start conversations with people I don't know. Also, I'm gay and I don't know how to tell what other girls also like girls. All of my friends are in relationships and I feel left out. I'm very ready for this to happen, I just don't know how. Please help!!