Yo Hamletcopter,
There are 3 things that you have to know to read music: notes on the bass, notes on the staff and identifying rhythms. Anyone of the 3 things missing or not at 100% and you can't read music. And in 20 years of teaching I find that very few people know the notes on the bass.
Test:
What's the 18th fret of the 'A' string? That's a question you should be able to answer without a bass in your hand.
I recommend that you get those 3 things down. And then I recommend that you buy a book to practice reading. I use the Arbans trombone method. Electric bass books are horrible! The are also some great cello and upright bass books. I like Simandl etudes also. You don't need electric bass books. You just need bass clef books.
I make a point to read a page a music every day. Maintaining what I already have is crucial. I never want to backtrack.
I hope this helps.
peace,
anthony