Talk to your pediatrician. I hate to automatically go to the behavior disorder diagnosis or anything like that, but it could be something like ADHD or even ODD (Oppositional Defiance Disorder) or it could be nothing along those lines. But I'd start with your pediatrician to see if he/she has any recommendations. Tell the doc that you have been told that your daughters behavior is similar to the characteristics of ADHD and ODD and you really wanted to find out more and possible speak to a specialist about it.
It may not be any of this, but if it is, you won't know until to seek help. Stop beating yourself up all the time. You probably did make some mistakes - we ALL DID, but you have to make a forward movement to find a better way to deal. Cut out all TV if you think TV is a problem.
You are miserable, but also, I'm sure your daughter isn't loving always being in trouble and probably not really understanding why.
I do have a son with ADHD and until we were diagnosed, Oh Boy what a time that was. Non-stop stress and arguing and the hubby and I simply not knowing what to do next. We went to counseling (meaning we took our son to counseling) and she ultimately recommended we get him evaluated. We did, we opted for meds, and have been very fortunate that the meds work without side effects. I truly believe he is happier, I know we are, and so is his brother, his teacher and his classmates. It took almost a year to get to the diagnosis and meds, and wow was that year very hard on all of us.
Feel free to email me directly if you wish to discuss further.
Good Luck
J.