I understand how you feel, I'm also a fellow Year 11 student and it has been demotivating having this extended period of time where we would've been able to completely understand the pressure of exams, how to keep revising and the nature of exam season. I've stressed way too much on how much work I should be doing and in the end I fall flat and give up on all the work I said I would be doing. However, what forces me to keep revising is the fact that there are several others in the same position as we are. They are definitely going to have to change the first intro classes for when we go to A-Levels as I know some people have done no revision while others have learn the entire syllabus for Year 12 Biology. The best you can do it do some light revision every now and then. Don't force yourself if you can't be that motivated to do something. Set a goal maybe, of how much revision you want to do. What topics and how your going to revise? A few quizzes. Go over your flashcards. Read over your notes. Go on BBC Bitesize. Watch videos. Maybe plan something with a friend and video-call each other to do a mini-recap session. I'm glad you let all this out because I have felt the exact same way until I talked about this with my friends and they reassured me they felt the same way. Stressing this much is not good for us so, chill out! Just know that we're all in the same boat.
Hopefully this was somewhat reassuring. Keep going and good luck!