Well, you asked me for help, so I guess this is the thread you wanted me to post it in.
Now, keep in mind that while I'm not a bad player, I'm not the greatest.
First, you should stop doing the slow lows online. Lows like 1A, A2A, and 3A+B are pretty bad offline at neutral, and would be punished harshly. Not that these lows never hit offline, but they are rather easy to block, but are made incredibly hard to block online. But do what you want, this is just a "morale code" for offline players to follow online.
Next, I wouldn't whore out 4KK as much as you do. The second K can be easily ducked, leaving you wide open for punishment. My dumbass contradicted this by getting hit with the second K nearly every time you did it. I was trying to TC it with Voldo's A+B. Using 4K by itself isn't entirely bad, as it can mess with your opponent's mind. You can also try 4[K]B:B, but don't expect that to fool your opponent all the time.
I also strongly consider learning Nightmare's frames. You were attacking even at -11, meaning you were doing i30 moves. That isn't good, as you saw. I started interrupting you with A+B and 3BB.
You need to mix it up a bit more. GS A is good, but if that's all you do, then you're going to have a hard time. If you know I'm going to duck, go into an empty GS and hit me with a WR B or try and space me with GS B. Against Voldo, his A+B shuts down 33B at close range. The only options you have against A+B are a DELAYED GS A or GS A+B.
Don't ignore 11K, its a beautiful move.
Also, you need to step. Stepping is beautiful. Overall, you need to learn when to roll, ukemi, and when to step. Get your momentum up by moving around, not just attacking.
In Engared's words, grab more. The more you grab, the more they'll duck, the more free 3B/33B's you get.
Finally, just read all the lovely guides our Nightmare mod Tiamat has posted. They're chopped full of material and information I didn't know. You'll find many tech traps, frame traps, combos, set ups, and all sorts of nifty uses for Nightmare's tools you can use to completely dominate and rape people with.
Oh, and one last piece of advice: agA. You seemed to have ag:A down, which is good because its +8. But you need to get A

A down, because its +1 AND its i14. Its yummy.
Overall, you've got a way to go, but you want to get better, and that's the first step to getting better. You'll get there, just stick to it.