Hey there. I'm not going to comment on GCSE requirements as I don't know enough. But being brutally honest, you need to do very well in your A-levels to be considered for Medicine. As it stands, your grades do not reflect someone getting A*s at A-levels. Of course you can work hard and get there, but this is where my advice comes in. Give up on Maths. Biology and Chemistry will be tough enough, and you'll most likely need to retake GCSE Maths to get a 6 anyway. Adding Maths to your A-levels will only make things more difficult, and without sounding too harsh your grade profile hasn't been outstanding thus far - in terms of Medicine grades.
If you have the drive, I 100% believe you will get there. But my advice is not to make that journey even more difficult, especially when most Unis will not have a strict third subject requirement.