| Lots of times when you're in the bass chair, you're not really required to play a lot of notes and run scales like guitarists do. Some people - especially non bassists - sometimes think being a bassist can be a little boring, but it isn't true. You can get a lot out of one note by getting into the feel of the way you're playing it, the attack, how long you hold it and how it's going to lead to the next note. It's like sinking your whole being into that one (or two or three) notes to the point where you're thinking of things about it, 'tasting' it as it were, more than a guitarist would with 50 notes. It's far from boring. It's more like you're putting your whole being, your whole intent into the notes you're given to play.
That said, that feel and drive and emphasis is, in a large part, produced by your picking hand, in your case the right. I mean it's great and all to play some flashy scales and runs now and then, but there's an incredible amount of depth in the nuances of how a single note is played - if you think of it that way.
I'd say, keep experimenting with the lefty bass (I'm a lefty too), but don't exclude the possibility that playing righty is the way to go (or get back into it), based simply on the fact that you can't finger complex lines. I don't know the extent of your injury, but it seems that your 'real' playing hand - your right - is intact.
It's probably really frustrating to not be able to do things the way you used to, or the way you 'remember' but that's the cool thing about music; it's a real 'now' sort of thing. It's what you play from this moment forward, not what you used to play, or how you used to play. And if you played in bands and stuff, you'll know that lots of times you're doing one note per bar (or four bars), and your left hand is doing nothing but holding that one note down while your right is doing all the work. You rip off a scale or something and everybody looks at you like "Man don't do that..."
After a 12 year layoff, you might find things about your 'new' playing that you never knew before.
Best regards. | 
