What if I'm alone forever?

I am a 25 year old man who left college about a year ago. Most people would agree that college is probably the time of your life when most friendships, relationships, and interactions are cultivated. Out of college I have basically one friend who doesn't live near me anymore. I see my sister able to hang out and speak with her friends all the time and I can't imagine going up and talking to people. What if they want to be left alone, what if I don't know what to say, what if I stutter. That isnt even including talking to a girl to try to ask on a date or something. It truly feels so insurmountable to overcome; cold approaching people.

With all that being said, I'm just wondering if I missed my chance to develop relationships. I feel like most people I know don't have hobbies or places they go to by themselves. They usually go places with other friends and meet other people that way. What do I need to do?