Your controls are so foreign to how I play with my sjas. I run my wasd as
W = Fly Up
S = Fly Down
A = Strife Left
D = Strife Right
KP0 = Secondary Fire
Mouse 1 = Fire
Mouse 2 = Open/Use
Mouse 3 = Move Forward
On my netbook (which I am currently using now), I alternate Mouse 2 with secondary fire and have F as open. The key strategy is behind my weird design is for speed only. I try to focus only on movement without thinking so much on whether to move back or forward as a Sjas. As such, I tap w and d repeatedly for the up/down sjas spam. The reason secondary fire is so far away is because on the PC, I really have no use for it because my evasion is much more precise. So I have the right click as open doors to pursue or flea much faster without scrambling to think of which position a command is on. As you can tell, most of my dirctional use is based on my mouselook direction for which way I am going.
On the netbook, I am not as good with a Sjas so I need secondary fire to repel attacks in tighter spaces.
I also use the arrow keys to move. I also use KP4 and KP5 to switch weapons instead of mousewheel (because I broke the wheel).
This is assuming Mouse 3 is the wheel when you push down. Then if I am right, and it isn't mouse 2, then I just use my middle finger and hold onto the button while I fly around and use wasd. With any other class, I switch to arrow keys (or on the netbook, it is UHJK, spacebar as jump).
A little arrogant to suggest that people try out my configuration, but some can vouch that it must be effective as I have a tendency to survive a lot of my matches either for a long period of time or with little health.. and it's incredibly lazy.
Also Marines are your worst enemy because of hitscan weaponry. I suggest avoiding direct confrontation as much as possible, and only come in when their back is turned (or they are facing something else entirely).