Since you enjoy your course then I wouldn't suggest dropping out.
Don't worry if you feel invisible to your flatmates, I made most of my friends that I go out with from my course and not in the accommodation. If you want to go out with your flatmates, try talking to them when you see them around and by seeing them more, you'll get more involved in the things they do and their nights out. If you want, try organise things to do together, it can be as simple as everyone in the flat trying to cook a meal together or you can suggest places to go for a night out.
I know this will sound cliché but trust me things will get better - it's really early into the year - so don't feel like you have to drop out.