Ok this is a really common problem
1) Try a timetable again - if you know that everyday you get homework for the next day then include that time in your timetable. It will help you gain some control over the situation and see in black and white how much time you really have. A timetable isn't just about homework it is also about revising your subjects, or reading ahead of your subject (especially important for Biology) - doing this should make your homework a little easier and quicker in the long run.
2) Use your time wisely - don't forget about free periods and school/college, or commuting time. If your time is pushed these moments can give you a valuable edge.
3) Don't spend longer on things than you need to - you have to learn when to stop. Sometimes (and I don't know whether this is you or not) students waste there time on ridiculous things that they call work - eg making maths notes for example. Or they sit down for a three hour study session but only do about an hours worth of work - there is a lot of staring into space, checking the phone, thinking about something else, staring blankly at the text book - STOP! If this is you you should employ the Pomodoro technique where you only work for about 20 mins at a time. It is a much more efficient use of time.
4) I hate to tell you that if you have done all of the above for a couple of weeks and it is still not working - then something has to give - either hobbies or work. Your A'levels are only two years and you want to give them your best shot, especially if you want to go to uni, give it your best shot even if it means sacrificing something else. There are exceptions to that rule - if your hobby is a sport and you are really talented and training for the Olympics for example - or you have to work for a tangible reason (not just saving for uni).
Wish you all the best - hope this helps