In queen pawn games (d4) you want to counter the center with c4 as white or c5 as black. Nc6 on your 2nd move blocks your c-pawn which is not very good.
12...dxc3 would have won a pawn for you atleast. If he played worse you would go up more.
For your queen chuck, at every move think, is my queen, king, or an undefended peice on the same diagonal/file as his rook/bishop?