toddlers aggressive behavior!

hey ladies! I need some tips on dealing with my two year old. I run a daycare currently and he is often really mean to the other kids. He steals toys, steals their special stuffies from home just because he knows it will upset them, but them, push them, pinch them, pull hair etc. all of my daycare kids are close to his age and none of them act this way except my son. it is not constant behaviour, but too much for me to handle. I'm also 3 months pregnant and starting to get overwhelmed with it. Not only that, but he often has a hard time listening to me. He will hit me, kick me, scream at the top of his lungs if I'm not paying attention to him for a couple of minutes. if he doesn't get his own way, he throws a massive fit. I have tried time outs in a different room. doesn't seem to work. I've tried time outs in his bedroom, but it seems it's having a negative effect on his sleep if habits (he now refuses to sleep in his room). how can I stop this aggressive behaviour??