What Am I doing Wrong?

My Little boy is 19 mts old, he is usually a very happy little boy, lately he has been showing signs of temper tantrums,kicking, sceraming, throwing himself on the ground. I am A single mom and its just the two of us expect from 8 to 3 on weekdays I babysitt a 6 mth old, so there is not much work to that. Everything I tell him not to do he dose. I also have the problem of him Hitting other children, even adults. Now I can't understand where he has gotten that from because I only "tap" his fingers when hes dose this. I dont feel that I need to spank him. Should I? My concern is that how to I teach him to be Nice to other's, share his toys, not to hit, and to listen to me?
I have tryed "time out" sometimes it works, and sometimes it dosent. I want my Little Boy to Be "nice", and "well mannered" But How do I teach these things to Him?I also have the tendency to feel really bad and sometimes cry after punishing him, I know that it dosent help. I am Hoping for some answers.. Please

[RockRose]

Maybe his father,  who you don't even mention,  gave him the genes to be a difficult child?

[sadmommyofaleah]

its the terrible 2 ,s   i have 2 toddlers and experience some of the same behaviour. i wouldnt worry about it to much , most likely he will grow out of most of that . i dont think its anything that your doing wrong , toddlers exspecially love throwing tantrums , its what they do best , just try to be patient when he gets to the end of the terrible 3,s it should get better good luck

[Shelley2007]

He also flys to the ground and hits/nips other kids/adults. Also he wont have any help off anyone and always seems to be having bad tempers. We decided to introduce the reflection step, we give him a warning first after a tantrum and then he goes on the step for 2 minutes if the bad behaviour continues. Sometimes it works and sometimes it doesn't, we too are at our wits end and he isn't even 2 yet?

[AHP84]

Don't worry about the tantrums, that's a very typical part of toddler development. I'd be concerned if he didn't throw a tantrum on occasion at his age.
That said, you're not doing anything wrong. Sounds to me you may just need to redirect how you go about disciplining him.
First, let's start with what you want and expect from him:
- be nice to others
- sharing toys
- no hitting
- listen to mommy.
Those are perfectly age-appropriate rules for a child his age. So your job is to enforce the rules. This does not make you a mean person. You are helping your son develop into a productive and caring little man. People will appreciate that.
If your son is about to break a rule, or breaks one, give him one firm warning by getting down on his level and saying, "Listen to Mommy. Do not hit other people, it's not nice and it hurts them. If you hit again, you will go to time out." If he talks back, screams at you, has a meltdown, or goes and hits again after that warning, place him in time out. No ifs, ands, or buts. Just do it without further explanation. Keep him there for at least two minutes. If he's calm, tell him why he got time out. If he's still pitching a fit, keep him there until he calms down, then tell him why he got time out.
You must stay consistent with this method. Don't let him see you "regretting" his discipline (you said you sometimes cry after punishing him), that will only give him the power to manipulate you, and believe me, he'll pick up on it in no time if he hasn't already. Don't compromise your authority to a 19 month old--you're the parent and he depends on you to raise him into a person that is well-adapted for society.
You asked if you should spank him--that's entirely up to you. I personally don't have anything against spanking if it's used as a deterrant for exceptionally bad behavior (i.e. don't wait for him to be behaving badly to give a spanking, but spank just as the bad behavior starts to put an abrupt stop to it). I believe if spanking is used after the child is well into the bad behavior, then it's useless and only encourages the child to hit back in the heat of his/her own temper. I spank my 2 1/2 y.o. son sometimes, and I've *never* had a problem with it affecting him in a negative way or making him more aggressive.
But spanking is a sensitive issue for all involved, so if you do not feel comfortable doing it, then find another way to discipline your child that is equally as effective.
Also, make a big deal by showing examples yourself. Show him how you share your things to be nice, tell him how you listen to other people, etc. Then praise him immensely when you see him displaying pleasant and obedient behavior.
The main key is to stay consistent with discipline. It may not seem to be working sometimes, but don't give in or give up. Maybe try something different, but whatever method you find that works, stick with it. And like I said before, don't feel bad for disciplining your child, and certainly don't let him see you regret disciplining him. Discipline is a necessary and inevitable part of growing up and learning. You should not feel bad for teaching your child proper behavior. The only time you should feel regret for something like that is if you abuse him physically and/or emotionally, and it sounds like you're definitely not abusing your son in any way. So don't worry. You're not doing anything wrong.
Hope this helps a little. Good luck!