When does play begin in Euchre?
Officially play does not begin until the dealer has discarded. 

(take the following quote with a grain of salt, there are tons of euchre variants and home rules that may contradict this). 

http://www.euchrelinks.com/rules.html


  XIII. If the eldest-hand leads before the dealer has discarded, he
  cannot withdraw his card and change his lead, nor can the dealer be
  deprived of his right to play alone. The discard is not completed
  until the dealer places his card under the kitty, or on the table, and
  has quitted it; and when the dealer has once quitted the discarded
  card, he cannot change it.
  
  XVIII. If any player plays with six or more cards, or, if the dealer
  plays and omits to discard and fails to announce the fact before three
  tricks have been turned, such player or dealer cannot count the point,
  or points, made on their side in the hand, and they lose the deal. But
  if the adverse party win under such circumstances, they are entitled
  to count all they make.


If you had stopped play and discarded after the first card(s) were played, they cannot be un-play their card once you discard (and you can use that information to choose a discard).

Since you did not discard and played the hand with 6 cards, you cannot score points this hand.