all the theory i know so far i learned from a book called bass fretboard basics. it covers...
*scales-major, minor, harmonic, melodic, pentatonic
*modes
*intervals
*how chords are derived from the scales
*basic voice leading and turnarounds
and other stuff like

can any recommend any books or websites where i can build on this knowledge.
also, what should i start to learn after this?

thnx in advance

I'd try to move on to compositional technique, voice leading and counterpoint. Learning why things that sound good sound good is very helpful. As my composition techer told me "You can't break the rules until you know what they are, and its how you break rules that defines your individuality as a composer".

all the theory i know so far i learned from a book called bass fretboard basics. it covers...
*scales-major, minor, harmonic, melodic, pentatonic
*modes
*intervals
*how chords are derived from the scales
*basic voice leading and turnarounds
and other stuff like

can any recommend any books or websites where i can build on this knowledge.
also, what should i start to learn after this?

thnx in advance

Exactly what the guy said before me. Now that you know all of that, maybe it is time for you to start playing along with some jazz standards (if you aren't already). Pretty much everything you covered goes along with jazz playing. I would also suggest that you learn every 7, 9, 11 and 13. Just arpeggiate them for every note.

Try The Jazz Theory Book by Mark Levine. It's been pimped loads here, and it is good. It covers most of that in the first part, so you should have a good grounding to approach it. It also tackles actually making music with what you've learnt, which is always good. Even reading the bits on the theory you know already is good. I find I get different takes on the same bit of info, which is very handy.

I agree. The Jazz Theory book is great!!!!