Ultimately, a year or two at this stage isn't a big deal at all, people have wasted way more years of their life and ended up successful. A person starting uni at 20 wouldn't even be considered a mature student, so I really don't see anything for you to be ashamed about. I don't see any reason why you can't still hang out with the friends you made this year either, even if they're moving on to their 2nd year you're still at the same uni aren't you? I understand it feels like a huge deal to you right now but trust me, it really isn't.