I've been using only 2 fingers with my left hand..

[imadestroyer]

I bought my first bass back in september and began playing it.. To tell you the truth, its my first instrument.. I've been playing every few days since then. Really casual, just kind of messing around. No teacher or anything. Well, just recently I decided I wanted to step it up a bit and get better. but I realized.. I've only been using my index and middle fingers on the frets. Is it okay to hold it like this? And if not, how should I go about retraining myself?

[dvh]

No. You should really learn to use all four fingers of your fretting hand. Your speed, accuracy and fluidity will all be better. There's a lot of info, a lot on the web, to help you. Start with the stickies at the front of this section.

[Tyler C.]

The odds of you going anywhere as a bassist playing with two fingers on your fretting hand are zero to none. A good way to practice would be just playing all the notes up and down the neck on each string, making sure that you use one finger per fret.

[ysand]

Find a good instructor for even a few lessons.
It's quite crucial to start with a good technique, and 2 fingers isn't a good one imo

[NickInMesa]

Start doing chromatic scales at the end of the neck.

Open E-1-2-3-4
Open A-1-2-3-4
Open D-1-2-3-4
Open G-1-2-3-4

Then 2 half tone up:

Open E-2 1-3 2-4 3-Open A etc...

[trust24]

it is hard to get all four of your fingers going. why not get a beginners instructors dvd and a few lessons