Figuring out songs by ear... problem?

[Stupidnick]

Hi.. Ive been playing bass for about 9 months..
Ive relized something.. I can figure a song out.. if my teacher or my dad tells me what key it is in...
Well.. I wanna figure out how to tell by myself..
I know there is probably not a fast way.. just... practice and getting your ear better for music..
How long did it take you to learn what key a song is in?
I really cant tell yet.. I have an okay ear.. cause when my teacher tells me the key.. i can tab the whole song out. .by scale patterns and modes hes taught me the past 6 months.. =D hes a great teacher and probably the only adult i can talk to about stuff. But I wanna figure it out.. Cause i get real frustrated
If you can help.. then thanks

[moley]

If you have a good knowledge of scales and modes and the like and what they sound like - which by the look of it you do if you can figure out lines by ear - then you should be able to pick out what key songs are in without too much trouble. While a song is playing, play any note on the nearest instrument to hand and hopefully you will know what the relationship is between the note you're playing and the root note of the song. That is if you can hear the root note in your head. At least that's how I do it and it usually takes a second or two to work out what key any song is in. If you're not able to hear the root note in your head, or sing it, then I don't know what to suggest, other than doing a lot of listening...