Hi

Where do you live in San Jose? There are tons of places to meet people but it all depends on where you are staying. Granted, anything I suggest will be on the low-key side.

I live in Tres Rios (so just outside San Jose) haha I'm open to suggestions

Thanks

I've up in Tres Rios a few times and it is very nice! I cannot remember exactly, but there was a nice small plaza/mall behind a McDonald's that had some great places to eat and hang out. Curridabat is close to you and has a lot going on. There are a numbers of clubs and hang outs, not to mention good restaurants too. Further is San Pedro (where we live) and there is a very active nightlife around. Lots of students too. Good places to eat. Although I have been to Cartago a lot, I don't know too much about it. Usually, we are just passing through.
It's a strange transition, I'll admit, but it helps if you join a few clubs or even a gym. You will find the ex-pats a little warmer than the Ticos, but that is more cultural than anything.
You really got to push yourself out there and it can be intimidating (I know!) but it is the only way to make it work in a foreign country.
Good luck!