Oh I thought you were in the US, so that took away half my advice and you're a STEM major, so that took away the other half. You definitely need to be in school for that.
I can tell you as a fellow former STEM girl, if you feel different from 90% of girls on campus (including your roommates), it's because you are. You just think about things differently and derive enjoyment from different things than they do. You're also almost certainly introverted and probably shy and that makes things harder to relate and adapt to a new environment and so you also dwell on a familiar comfortable environment (homesick).
The best thing I found is not just to "get out and do things", but with whom is most important.
My freshman year they had also sorts of activities to help you get to know other students and involved and these were horrible for me. They were all doing things you don't enjoy and also made you stand out from other girls and boys which made you feel worse and isolated.
My advice is it get involved with people and activities you'll fit into and enjoy. (Especially first year to get comfortable and build a friend foundation - later years you can branch out.) This means doing things and activities specifically with groups in your study area. Their mindset, humor, interests, way of thinking and relating will all be more comfortable.
A warning though, most of these will be guys. Be careful not to become a "STEM slut". It can be very easy to be surrounded by 10:1 guys and enjoy the attention, but it can be very bad for your development (and reputation). Concentrate on making friends with other girls in the field and with the guys be friends but rebuff advances early by saying you're just concentrating on your studies right now to make sure you do well. Spend all, or at least most, of your first year with guys just as friends so that you can learn to recognize differences in their attention (and intention) and also meet plenty so you can decide who you actually like versus settling for attention that makes you feel good.