My son was hitting & pinching everyone until I implemented timeout. I tell him if you hit you sit! After a few times sitting in timeout his behavior improved drastically. I think kids need discipline and reinforcement, it makes them feel secure. Just be very consistent with it. My son will be three soon and he does have some underling issues including some speech issues. He has seen a neurologist and autism was ruled out. He has received early intervention services and he has also shown a lot of improvement. He is still hyper active but I try to keep his environment as calm as possible. I limit his exposure to things that may be too stimulating to him like the TV, loud noise or too many people. I try to stick to a routine. I stay calm even when he is not. A hyper child can be really frustrating but I try to keep a calm tone with him.
If your son has reached all his milestones and seems to be developing normally than I would not be too concerned. However, if he is not on track with his milestones I would contact early intervention for an evaluation asap (its free and it would not hurt). My doctor also said my son was right on track but early intervention found him to be delayed. It is not uncommon for toddlers to hit and push, but instinctually if you feel like something else is wrong I would look into it. Good luck (((HUGS))) I know how you feel, but it does get better!