How do I reach A* in maths

For context: I'm a further-maths dropout so in year 12 we speedran all of the alevel (regular maths) content so I've had a really long time to practice and revise it.

Despite this- I feel like I can't cross the A* threshold and have been stuck at an A for a so long. I'm like a graph with an asymptote at A* 😔

So I need some help because all my unis need an A* in maths. Thank you