Bev, you aren't doing anything wrong. However, he is fighting with you because he wants to wear you down to get what he wants. You must not let him.
It is good that he can say short sentences. Use that ability to foster his communication. When he gets mad or starts crying, say to him "Use your words" and say it often. Daycares use this to help children SAY what they feel instead of SHOW what they feel (with hitting). If a child hits, they put the child in time out, every time. I know you say it isn't working to put him in time out, but perhaps the thing you should do is put him in his room or in a playpen (that he cannot climb out of) if he hits you. That is a more effective time out. Then walk away from him for several minutes so that he is by himself.
NEVER let him off the hook for hitting you. ALWAYS give him the same consequence. Right now you are trying a bunch of different things, and that's not working. Instead, deposit him into a place he can't get out of, away from you. If you aren't dealing with him, he can't continue to fight with you. If he screams in time out, WAIT HIM OUT. He will learn that screaming and crying do NOTHING to get what he wants. Don't let him know that you are listening outside of the door or outside of his view. When he calms down, you can walk back in and say "Are you ready to behave?" Make him say he is sorry for hitting you - and then take his hands in yours and say "Hands are for helping - not hurting." Do this every time.
Continue to prepare him for upcoming transition. If you need to, use a timer - tell him that when the timer goes off, you change to another activity. If you find that TV causes the biggest problem, drop the TV for an entire week. When he cries for it, tell him that he is crying too much over the TV, so he has to take a break. Truly, I have a feeling that the TV is mostly for you, and you need to give up that idea so that you can deal with your son's misbehavior RIGHT NOW.
So, to recap - one or two transition reminders - "As soon as the bell goes off/TV program finishes, etc, we will color". Crying ensues - get down at his eye level and say "Use your words - tell me why you are crying". He hits - grab his hands and hold them tight and say "Hands are for helping, not hurting" and then tell him that he has to go into time out because he hit. Immediately stick him in a play pen or take him to his room and put him in there and shut the door. Hold the doorknob so that he cannot get out. Do NOT let him know you are outside that door. You do not open the door while he is screaming. Wait til he is done.
You will not get much done at home when you start this process. You have to consider this a big deal, getting him to understand that THIS is the way it's going to be. So keep steadfast to your plan. Helping him TELL you that he doesn't want to stop what he is doing is good - and you AFFIRM with him what he is feeling. "I understand that you are mad that the TV program is over, but it is time to turn off the TV." And don't give in. Never give in to a tantrum or when he hits you.
Good luck.