Do I have a chance at LSE?

I wouldn't have any doubts if I were you, but we can't say what your chances are like, particularly since the majority of the weighting of an application is on the personal statement if the grades are satisfactory.

If I am quite honest, i'm not very satisfied with my personal statement, although I have a good amount of ECAs (Football, Volleyball and Basketball) I don't really have many supercurriculars and I think my IGCSEs are a bit weak. So idk I feel like 2 (and potentially more downsides) in my application would let me down.

You have a lot of time to work on it if you haven't applied yet. You can always do some extra reading or research (perhaps use LSE's recommended reading lists as a guide) and find things that would be good and suitable to include.

You don't have to "do" a lot of things to write a good personal statement, sometimes if you have an interesting idea or theory about something related to your course you can explain that and it would be very interesting for an admissions tutor to read, and it would also demonstrate your passion for the course.

Edit: regarding your school not offering further maths, normally LSE sends out a survey to applicants who don't have it where they can fill in why they don't have it (and what other maths qualifications they might have), or at least this was my experience applying to Econ there.