No friends

I’m 27, almost 28…. I used to have tons of friends growing up but when I hit my 20s idk if it’s autism or social anxiety but something happened where I isolated myself badly. I have a bf now but I don’t have any friends and I genuinely don’t know how to socialize with girls my age. I went to a family bridal shower last night and I just felt depressed afterwards knowing that I’m probably never going to have that in my life. I don’t think I’ll ever have friends at this point. I feel like it’s all my fault.