How do I get two days of homework done?

do as much as you can every day ... weekends are for catching up, right?

If a problem is too big, divide it in half and only tackle half the problem. If the half is too big handle, then divide THAT in half taking only 1/4 of the problem. 

That is, pace yourself. Don't look at that mountain of work or you'll be overwhelmed by the enormity of the mountain. Instead, divide your work up into smaller chunks. If you have six hills instead of mountain, you can conquer those hills one at a time. If any of the hills are intimidatingly big, divide them up into smaller sections too. 

Put some of your other activities on hold so you can devote time to "playing ketchup" before and after school and on weekends. Gradually that long list of "hills" and "sections of hills" will grow shorter and shorter. 

If you're not sure what your priorities are, which "hills" are most time sensitive, most urgent, ask your instructors or an academic counselor to help you plan your work. The planning is the hardest part. Once you plan your work, then you just work your plan, trudging away step by step by step until you get there. And get there you will, so long as you're moving steadily in the right direction. 

By catching up on it and not wasting time on the internet and your mobile phone.

Tackle the toughest tasks first, and be persistent in your effort to plug away until you’re caught up.

Besides research on the internet if you don't already, there's nothing much you can do