Hello Stanley,
Glad to know that you are a highschool student and have interest in robotic. From your user profile knowing that you are located in Macau while I am in Hong Kong that is near to you.
I suggest you to use driver ICs because robustness and size seems are the two important issuses in your application. I just found a website about this stuff, you can go to there to have a look. The address is "http://www.robotroom.com/HBridge.html".
Finally your design seems use the 51 core as your controller, as I know most designs from Mainland China are using the 51 core MCU and there are lots of 51 experts in Mainland's discussion forum such as the www.21icbbs.com and www.mcu51.com/
Try to go to there to have a look.
Good luck to your project.
Best 73 from Li.