Extremely closed game
After the opening you had clear advantage on the queenside due to you extra space and white's chances for counterplay as far as they existed lied on the kingside (preparing f4). Therefore it was positional mistake by black to allow the complete sealing of the queenside (ending with 17. b3!).
Instead of 15... b4 typical move for these positions would be 15... c4(!) attacking the base of the pawn chain. Later black can for example consider the manouvre Nd7+Nc5 and either systematically play along the c-file or perhaps breakthrough thanks to some tactic. Anyway, the most important things is not to let the opponent completely seal the wing where you are stronger.
After the opening you had clear advantage on the queenside due to you extra space and white's chances for counterplay as far as they existed lied on the kingside (preparing f4). Therefore it was positional mistake by black to allow the complete sealing of the queenside (ending with 17. b3!).
Instead of 15... b4 typical move for these positions would be 15... c4(!) attacking the base of the pawn chain. Later black can for example consider the manouvre Nd7+Nc5 and either systematically play along the c-file or perhaps breakthrough thanks to some tactic. Anyway, the most important things is not to let the opponent completely seal the wing where you are stronger.
Thank you, 15...c4 does look like the much better move. I guess every pawn move really does count.