Fellow architecture student here, 3 years in. Take a look at your work now as opposed to the work you were doing a few years ago, you will undoubtedly see an improvement, and that's down to your hard work. It's easy to get impostor syndrome doing this degree, since everything is so subjective and the workload can get unmanageable. I can also imagine that London gets to be a lonely city, I have lived there for a short period myself. If you're finding yourself in a rut and repeating the same year to no end, it could be time to consider another degree. Architecture isn't as financially and emotionally rewarding as most think, so one of the main reasons to stay in it is simply passion for and interest in the subject. Put yourself first, please, everything will work out!