Nd4 doesn't lose a pawn due to a well known trick - Qg5 (after Nxe5)
You were right about d5 not only does it not work tactically but you shouldn't try to open the centre when behind in development unless there's a good reason for it.
Don't be too annoyed about the loss - these kind of moves are often played in blitz and the only way to get better is to make all the mistakes at least once
This game is not my finest hour. I've tried to show you what I was thinking as black, and perhaps it was 2 unpleasant blunders, or perhaps white's good opening strategy, or perhaps my desire to do anything to avoid 4 knights again, that led to my demise here. Certainly there is a lot to choose from.
I'd be grateful for all comments, particularly ones that won't make me want to give up chess and weep in a corner.