Take a look at this from a perspective of reality:
When you engage yourself in full-time employment, you will be working with people who are 5, 10, 15, 25 years older and younger than you (perhaps for you, the latter is a little extreme). What will you do? Leave and hope to find a job where everyone in the same age? We are all humans. We all have things we like and dislike. It may come as a surprise to you but people who are 16 will have similar interests as people who are 66. There will just be less of them.
You are involved in a society, great. They are not socially active, not so great. But - I'm sure your university will have hundreds of societies. Just join a load of them! Yes, there'll always be that awkward first time, but life is about awkward first time's and then getting over them.
I would break down the barriers that are holding you back (yourself) and really make the effort. The fact you have reached out here is great. You can build on this. If you want my experience:
I am 33, I attend university. My university friend group ranges from people who are 18, to the odd mature student like me. We are not wildly different people, we share similar interests. I never once feel like they think I'm a weirdo or whatever. If they did, I'd just drive myself insane with anxiety. If they thought I was weird, why would they spend time with me? (Maybe they are weird themselves, hmmmm). The point I'm making is that you can make friends, you just have to put yourself out there.