You're uni experience sounds A LOT like mine; I was at a good uni and thought that everything was going to be fine, but then the bullying started with my flatmates- they would have conversations about me and make fun of me in the flat when they new I was there and sometimes they would do so right outside my door.- At night too. My parents even intervened by speaking to the ring leader, but that just made it worse. Threats to tamper door my food was the last straw, so I reported it to the uni (formally), and I moved to another halls. That was much better than my other halls in the beginning; the flatmates seemed much more welcoming, and I made good friends with an international student from America- something I didn't get the the chance to at my old flat because they weren't very nice people.
But soon my other flatmate (there were only three of us) was hell to live with, and she would bring a gang of boys over. They would mess up our communal area, get drunk and do some disgusting stuff (all at random hours of the morning, which really started to annoy my other flatmate and I). This even happened at exam season, despite the halls having rules about noise etc for those weeks.
And if I thought it couldn't get any worse, the flatmate and her friends knew the other people that I lived with before and she started treating me weirdly, and her mates started harassing me; banging on my door and purposely doing stuff outside of it in order to wake me up and coax me out of my room.- This mostly happened when my other flatmate was away.
I eventually got through exam season and finished the year, but after that I didn't want to go back- especially when the uni did nor do anything about the bullying, despite their so-called "zero-tolerance" policy.
On top of that, I ended up failing one of my classes (despite working so hard on it), so I didn't pass the year.
I find that whenever I get asked abour my time at uni (and when I was at uni), I always felt awkward and didn't know how ro explain what I felt about it because I couldn't see what was particularly good about it...I guess the best things were my course, coursemates and meeting my American friend- we cried and hugged when we said goodbye.
The independence was also good; I loved the feeling of going out to get my shopping, late night study sessions in the library, the relief I felt after completing essay assignments after spending days on them, and I especially loved the feeling of travelling too and from home, across the country on the train by myself.