You're doing the most academic subjects so I'd assume you'd get tons of homework. You just have to find extra time. A have a few friends that do it and they use their free periods (sixth form) efficiently, as in they basically teach themselves a whole topic in an hour.
If you can't keep up with the workload, think about dropping one. If you don't want to do that, just explain to your teacher/tutor that you can't deal with how much work is being set. I know currently my friends are getting insane amounts of chemistry homework to do and they are having to spend their time very wisely.