I feel bad about not having a partner
I'm sorry to hear that. It's never too late to find a partner.
Perhaps it is too late for me
You shouldn't feel that way. You have much more self-worth than measuring it with having a partner or not. Being single has its benefits too so you should just be happy with your life and go out and do things that you want to do without needing to answer to anyone.
It is hard to do everything with myself.
Have you tried looking online on forums and places that match your specific interests? Maybe you can find someone who is also interested in what you like to do and talk to them. That way you can have something in common to talk about when trying to build a friendship.