Hi Gilan,
10. Nb5 indeed is pointless. Either go for Na4, or defend the pawn on e5. Once the latter falls, black breaks out. Remember that a large part of the idea of the French is to try to keep the black's light-squared bishop blocked in - one you fail at that (and lose the pawn, to boot), you're in trouble.
Trading bishop-for-knight on d4 yields a weak pawn on that square, but on the other hand, you now have the bishop pair. Use it!
19. ...Na7 sets up a trade of light-squared bishops. Instead of 20. b4, you should develop your rook with Rc1. This also avoids the bishop trade.
24. f5 made no sense to me - I would've played Be7 since that diagonal is nicer. Instead, you let your bishop get booted, and ended up blundering it.
I can post more games if that's relevant.
Thanks.