Someone's just frustrated because I'm beating them to 200 AAAs.
Honestly, I thought your AAA count was going to shoot up right away. I think it's partially a focus issue and partially a lag issue for you. In order to FC the songs you have FCed (especially one-handed), you must have incredible rhythm resolution; i.e., you can perceive very small differences in rhythm over time. That's all you technically need to AAA these easier songs.
The trouble is (as Patashu is very aptly pointing out) that the notes, despite being farther away from each other in time, still must be hit within that 3 frame window, so you must really focus yourself on the amount of time the silence (or blackness, if you're playing solely visually) in-between notes takes up to know where those 3 frames are at. So, on tougher songs you actually get additional information by having more frequent notes, which it why I think it takes more poise to AAA on the easier songs than the harder ones. There are other reasons for the harder ones being hard, but that's mostly straight technique, which you obviously have plenty of.
I still play with the audio on even if the sync sucks, because usually I can make some adjustments visually, and the audio can help guide me in a more general way (mostly so I know what part is coming next). Autofail is only useful when you have a blackflag or a booflag, where you can
So,
#1. Get a subbie. I'll see what I can do to help you out. You should PM me with what you can afford credit-wise and perhaps we can work out a special credit pricing rate for you for a 3 monther.
#2. Buckle down. Keep practicing at it. It will get easier.