What should I have done with my bad bishop?

After d5 (instead of c5 which I played and is a blunder of course) what should I do with my lightsquared bishop as black?

It's not really that "bad" of a bishop (at least, not at the moment). :)

@MrPushwood yes but what could be my long term plan to exchange it or make it better again?

A good plan might have been to exchange the LSB immediatly after white played Bc4, and follow it up with d5. Very solid structure, excellent central presence, nice harmony between the pawns locked on light and the dark squared bishop, and the e5 outpost for the horsie.

It seems like a solid approach. If it works tactically I think it would be a nice position to play

@thoughtless2 I thought about that too, but the engine thinks it is a blunder and I guess it is because the white queen is suddenly very active while the black queen seems to be doing nothing anymore where it is and has to go back. Also it would lead to a very positional game and no attacks and white can start a minority attack with c4 breaking the pawn chain and getting rid of the double pawn.

Indeed. It looked like a natural plan to go for but I guess it wasn't compatible with the nature of this position

Please more responses from good players.

It won't remain a Bad Bishop because c5 will come anyway.
13 ...d5 14. Bb3 O-O 15 c4 c5

The point is to gain 2 tempi by attacking white. d5 comes first because it is supported by the c6 pawn. then afterwards c5 comes with an attack on the queen. you may choose to push d4 to close the position or to capture on c4 and exchange bishops and start a pawn storm on the queenside with b5 and a5.

The bishop is not bad at all.

"Bad Bishops protect Bad Pawns (but for a Good Reason!)" (Watson)