Hi, I just stumbled across this thread and I just wanted to say that first of all good luck! You got this and I'm gonna be rooting for you!
Secondly, I don't know if this will help but I was also in a similar situation. Throughout my GCSE years I played academy football so I was very busy constantly and I struggled with balancing my GCSEs with my football career. In the beginning I did really poorly because I never learnt how to revise and would just rely on turning up to lessons and hoping I remembered everything. In year 9 I was lucky to have a teacher who did a 2 hour workshop on how to revise properly and so I did my best. I did really well in the end coming out with a handful of nines, majority of 8s and a 7. This was after being predicted 6s and 7s based on my mocks so I ended up proving whoever does your predicted grades wrong.
By the time I reached A-levels, I was sadly released by the club and instead I just played a lot of semi-pro/non-league. This allowed me more time to focus on my studies and one day I just woke up and decided I really wanted to do medicine, I just felt so inspired by a documentary I watched called the Surgery Ship. At A-Level I struggled in the first year with Biology, I would scrape by with Cs a couple of Ds and one time I got really lucky and got a B. In the end of year exams which would determine your UCAS grades I was absolutely terrified. But at this time, I was revising properly, I knew that if I wanted to do medicine I had to prioritise my studies not football so football took a backseat for me. I managed to do well and scrape an A in biology by I think by around 3 marks. I did well in chemistry and psychology so I was applying to medical school with A*AA.
In second year I knew that this needed to change, people applying to medicine are some of the most intelligent people in the country and I knew that I had to do even better if I wanted to stand out and earn a spot. I spent the summer between first year and second year revising for my UCAT and BMAT and ended up doing really well in my UCAT (2950) but really mediocrely in my BMAT (4.4, 4.6 and 4.5A). Second year was hard for me, people were turning 18 and going out and I was always either revising or playing football. I did let myself go out a couple of times and it was fun but ultimately getting minimum AAA was my goal for the year. Around 3 months before my exams I decided that it was time to grind. I stopped playing competitive football and instead after lessons each day I would go into the library and grind for about 2-3 hours. By the time we were on study leave I was averaging 3-4 hours a day for revision, but I always took weekends off to look after myself. I was lucky that I had friends who decided to join me and this made it so much easier to have others with you. It was hard not to go out and socialise as much but it was a sacrifice I was willing to make to have a banging summer and hopefully study medicine in September. My hard work ended up paying off and I managed to achieve A*A*A* and now I'm studying medicine.
The reason I'm sharing my story is that I was in a difficult place at the end of year 11, not knowing what I wanted to do. At the start of college I was struggling with the jump and struggled academically. With just a couple months of hard work I was able to turn that around. I'm not the most naturally smart person so I relied on hard work rather than natural intelligence and it paid off. I've been in your shoes and I want to let you know that you can do it. Don't doubt yourself, you got this. I'll be following this thread closely, I wish you the best of luck.
P.s sorry this is so long, but this thread reminded me a little of my situation when I was at your stage, so thought it might be useful.