Anybody got advice on hanging out with friends?

Like, I have friends. I really like them, but these months I feel like I just don't fit i with them. It's mostly because they talk about topics I don't know much about or just aren't interested in. 

I seriously feel sad while in school because in our friend group there is like eight people, and somehow I am just on the sidelines. Like, I don't feel like I'm a part of the group but I am. 

Easiest way to gain conversation topics is fpr me to start living my life so I would have something to talk about with them, but have no idea how to do that eitehr. I have hoobies, but I think one would need to find things to do outside the house to become interesting.

If anybody has any ideas on best way to gain hobbies outside of house that one can do alone or meet other people thro, I would realy like to know.

I really don't want to be alone but somehow get the same feeling while in these situation.

Ps: here is a pic of my current chroche project. I am making leg warmers for my ★sister★