Should I do a second degree, a masters degree, or am I cooked?

I (25F) graduated from London College of Fashion where I studied fashion marketing and graduated with a first class honours. Since then, I've pivoted to consulting where I've realised that I want to pursue a career in finance. With that being said, I feel really limited in terms of careers I could pursue given that I don't have a strong quantitative background and didn't go to a target university.
I've considered either doing a second undergraduate degree or a masters degree in finance, but I did really badly in my A Levels due to a factor of reasons (mental health, undiagnosed ADHD, family problems, moved colleges halfway through year 13 - it was a terrible time) and I don't know whether I stand a chance unless I retake my A Levels. I've also considered retaking my A Levels, but I don't know whether this would make sense given that I already have a degree and I'm working.
If anyone has any advice or suggestions on what to do, I would really appreciate it. I know my university and employer would write good references for me, but I'm worried my academic performance is holding me back and I'm not sure how best to go about this.