Do I lose a card if I roll 3 bad luck symbols and spend some of them?
Yes, you still suffer it. Clarified on the back of the rulebook:


  
  Pension 
  – This card costs 2 bad luck. If the player rolled 
  3
  bad luck (causing misfortune and the loss of some card), 
  the
  player can still use 2 of those bad lucks to buy this card
  


Although it's true that misfortune happens after buying cards but before adding them to your CV, which is a very weird phrasing indeed, you have to suffer it even if you had previously "spent" two bad luck faces for the pension. Spending dice doesn't mean that you never rolled them.