I'm moving schools but I'm not sure if it's the right decision to make

I'm currently attending a Gymnasium in Bavaria, Germany after learning the language for roughly a year. I'm Asian, turning 17 this year, English is my second language, German is my third. At first when my mom suggested that I should study abroad in Germany in order to go to a german university later on since it doesn't cost too much, comparing to universities in other english-speaking countries, I happily agreed to her proposal. I thought it'd be a worthwhile experience, and turns out it have been one, however I must say, fair and square, I'm not happy with where I am right now. I used to be optimistic about everything, more outgoing, more open-minded and much much happier. Ever since this school year started I've become quiet, withdrawn, negative, hopeless; I felt like the real me is dead. I struggled once again with anxiety, fear of even the thought of having to get up everyday and drag myself to school, friendship issues and lack of support from the school staff. I knew best that what I was going through at the moment was just preliminary and that there must be a solution to every problem, so I tried to reach out, seek for help from a counsellor, connect with people in different ways but nothing really worked. Frankly, I've been considering changing schools for months and months, and I did apply to two schools (just in case I'm not able to get into one I could still go to another since I'm determined to move schools), one is another german Gymnasium where three friends of mine go to (the program is easier in this federal state where this school's located), another is an IB school, I don't know anyone here and I'm aware that the IB program is difficult and challenging, only suitable for organized and hard-working students, nevertheless I'd made up my mind and resolved to do my best if I could get in. So I'm kind of halfway in the application process when this girl begged me to stay and promised that if I stay here I'll never have to feel this way again because she'll always be by my side. This girl is actually a friend of mine albeit there'd been bad blood between us, she did a few things that made me lose trust in her. She only got me and another Vietnamese friend, we're rather intimate strangers than friends, we know each other well, our moms know each other well, we've been studying together for almost two years, but something is always there, there's no closure in our friendship at all. On top of that I put a lot of pressure on myself about getting good grades, I know it's bad but trust me, it's a helpful source of motivation for no one here believes in us, the teachers at school would have told me that getting a 4 (German grade scale: 1-6; 1 is best, 6 is worst) was way too good for a foreign student and that there was no need to try harder whatsoever. The counsellors at the boarding school treat us literally like kindergarten kids. Besides getting into a german university is what my mom wants, I want to pursue my studies in England, which is exactly why I think going to that IB school is the best choice. My heart tells me that I should go, but I'm still somewhat unsure, part of me wanna leave part of me wanna stay, I'd feel guilty if I go, I just wish that people cared enough before. I'm also a bit afraid of getting used to a new environment yet again. I mixed in the wrong crowd here, I'm scared that the past would repeat. I'm just eager to be a new person at a new place, to put it briefly a new start. But what if changing schools doesn't solve any problem? What if I screw up? What if it's not the right decision to make after all?