No friends at sixth form

Hi,
I'm currently in Year 13 and have no friends in sixth form. For context, I changed schools at the end of Year 11 for sixth form and changed from a mixed comprehensive to an all girls grammar school. Most people at the school were internal students and seemed to be in friendship groups. A lot of people also came schools in the local town so knew each other from there. I have tried really hard to get involved through extra-curriculars (I have done choir, art club, school play etc) and did ask to sit with different groups at the beginning however people sat in groups of 10ish and I'm a shy person so found this very intimidating. Didn't recieve any support in terms of making friends from new school and am always hanging out by myself. Would appreciate it if anyone could give me advice or could share similar experiences? Thx