Friends. What are those?

So I'm 17 about to turn 18 and realized today that I've never actually had friends before. I mean yeah, I've talked to people, I've been to sleep overs (when I was younger), and in school there's always more than enough people to talk to, but when it come to going out, birthday,parties or just any of the typical stuff requires you to not be alone in existence I don't have anyone. I do have my boyfriend but I personally feel so pathetic that that's all I have. I have no idea how I'm dating someone yet don't have a single person to talk to. At this point I don't think I ever will. There are people who are in their seventies and were just like me when they were my age. I've met a lot over the years. I have a feeling that might be one day. Everywhere I look people seem to have a support group or something. I don't. I want to go to college but know I'll be in the same place I've always been. Alone in a crowded room. I'm terrified of being all alone in a place where I have to become an adult. Does anyone else feel like this or have felt like this? What did you do to fix this? I really need some advice before it's too late for me.