Greetings Vibovit ,
First of all ,congratz on your win
You played 14....,Nd5 to exchange some pieces...seeing your position left after exchange ( better pawnstructure ( majority on queenside ),etc.. ) was a good idea ....only the move 14...,Nd5?? is a blunder ...it looses a piece. Instead of the played 15.Bc4? white should have played 15.Nxd5! a) 15..., Qxd5 16.Bxb4 or b)15...,Bxd2+ 16.Q (or R)xd2 and looses a piece.
Instead you should have played 14...,Rad8 to complete your development.
IWYW,
Yahto