yeah... I think making friends is hard in general and there really isn't much you could do if you already tried to make friends but they just don't work out. I would say think about another sixth form. What helps me not feel lonely is just watch my favourite Twitch streamer have fun with other people. He's greekgodx and I watch vods of him talking to his online friends that he was able to interact with becuase got some fame on twitch. I feel less lonely becuase whenever I watch him I could relate to him. He never really had a friend and spent over a year isolated by himself playing Rust all day alone or watching YT vids. But becuase he now has a big audience he can share how he felt so depressed for so long and makes me personally relate so much to him and helps me to just hear another persons personal struggles to know I'm not alone.
Other than looking for people you like to watch on YT or twitch, I would say try to put effort into loving yourself. if it is taking a 30 minute walk or taking time off to just focus on your mental state and see what you don't like but uplift yourself and comfort yourself.
E.g. i for real had no friends at all in school so when it is the end of the year and in our school you get everyone of your friends to sign your shirt I will miss out on that becuase I'de rather stay home than with 2 names on my shirt. I also won't have any friends in 6th form. But who cares. The majority of people don't even keep their friends in highschool. There is always more chances like in uni or at work if you get a part time job or someone on discord or somone at the gym. Noone or at least for me, I can't remember how I even got friends or what our first conversation was about becuase friends come randomly at random times. You seem like a cool guy so cool people will attract other cool people. Just like boring people or just plain stupid people will attract other boring or stupid people (like bullies lul). But those people who could be your friends probably aren't in your current sixth form.
So overall:
• experiment with twitch streamer's like (idk Andy Milonakis or whoever)
• read about what other say about their experiences of having no friends in general or in sixth form
• learn to love yourself and take care of yourself
• uplift yourself and STOP putting yourself becuase you probably do but you just don't notice it
• explore another sixth form but you probably will be in the same situation like you are now so focus on your grades and explore what you like to do I guess
If you need someone to talk to you could send me a message on this site and we could dm on discord becuase It could benefit the both of us. I'm fine with it even if you say no now but in 6 months you say you might as well. I already know I'm probably going to ask the same question when I go into sixth form probably too lol ;D
Hope the best!!!