Did I play this QGD correctly?

I won by resignation, but what did you guys think about my moves? I don't have a game analysis program or anything so I have no idea.....

You played reasonable moves.  Your opponent completely hung his material.  You took it.  Well done.

I am aware of that but my question regards if I could of a better moves on select moves.

You guys played mainline until your opponent went wrong with 4...Nc6. It's been played by much stronger players than me but I do not understand it. It seems like a waste of move as the knight will have to go somewhere else to allow black's c-pawn the freedom to move.

6. Ne5 kind of bizarre move. Why not continue development with simple move like e3? 6. Ne5 is dangerous move to make if you are someone who wishes to have smooth development. It's also good to keep in mind that letting black have your gambit pawn en-prise (free for the taking) too long in some QGD/semi-slav positions can spell trouble for white. (Have a look at 1. d4 d5 2. c4 e6 3. Nc3 c6 4. Nf3 dxc4)

9...b5 black attached some kind of big importance to this c4 pawn and decides to trade his c6 knight so that he may keep the pawn for the time being.

welp

edit: Forgot to actually answer thread title directly. Overall you played fine.