Nicky,
I'm just going to be straight with you here. You need to practice like everyone has said, the basics. I think you have actually performed worse on your Pull Me Under Cover, than you did on some of your previous ones. You need to stop trying to sing Dream Theater, and try to sing something simpler.
When I was starting out on guitar, I didn't go straight for Dream Theater or Metallica solos. I learned how to play nirvana solos. Importantly, I practiced them over and over in order to get them right. Once I was mastering that, I moved on. Now I can play the UAGM solo pretty well. And that is the course of 8 years of practice.
You really need to start from the beginning if you want to get better. Let me emphasize, you NEED to start from the beginning. Get a new vocal coach ASAP. Sing simpler and easier stuff and slowly expand your singing. You can't go from noob to JLB and Bruce Dickinson in a couple weeks. Sorry, it just won't happen and you just don't have the innate talent to do it. But that's OK! You just need to make up for it with hard work so you can make some progress. I'm not saying hard work will make you extremely good. It's not easy to be JLB vocally, that's why he's in a big respected band and highly regarded and most of us aren't. If everyone was that good, then no one would care about talent, there would be nothing special about it.
So you really need to go back and work your way up from the bottom. Stop posting DT covers for people to hear, because man they are really bad. You are all over the place in pitch and tone.
Don't cheat yourself man. Do it right.