Don't be nervous to go alone, anon. You're there for God, not anybody else.
I'd say in most Catholic parishes it's like this, if you go in and don't interact with anyone, then nobody will bother you. Of course, there's always options to socialize with people (outside of mass, such as at parish events, Bible study, youth group, etc). Most Catholics don't go to mass for any real socialization.
Let me know if you'd like to find know any specifics about Catholicism, but here's some basic info to start you off: https://www.catholicscomehome.org/your-questions/
May God bless you!