help me adjust to my new exercise schedule...? Im so tired..?

So... recently I split up from my husband, i had to move kind of far away because our old house was too expensive. So now Im living really, really far away from my kids nursery, and the only realistic way I can get there in the morning is by bike. ( I have a bike with a child seat, also I cant drive, and it would take longer by taking a train or bus as there are at least 3 changes and a 15 minute walk either side of the train station. )

Currently, every morning I'm cycling from my home to her old nursery which is about 8 miles, and then another 5 miles to my job. And every night Im having to do the same route. I was fairly active before - I would do about 8 miles a day - but doing this route every day (it has a few really big hills and its with a 16 kg kid on the back of my bike) has left me absolutely exhausted after 3 weeks. I have to keep doing this until april at least, and was just wondering if someone had some tips to help me get less tired? Im going to bed pretty much at 9 every night, until 6 am, but Its just not enough. Im physically exhausted, not sleepy, and I know that exercize is good, but when you dont have a choice, its not fun anymore.

Any suggestions?