Is a delay in pregnancy a punishment from Allah for wishing the third pregnancy to be a male, or for being content with the existing offspring?

There is no harm in desiring to conceive a male child, as long as it does not involve disliking the birth of females. Delayed conception may be a trial from Allah, so meet it with patience and abundant supplication. Continue to seek healing and have a good opinion of Allah, for He bestows offspring upon whom He wills and withholds it from whom He wills: "To Allah belongs the dominion of the heavens and the earth; He creates what He wills. He gives to whom He wills female [offspring], and He gives to whom He wills male [offspring]; or He makes them [both] males and females, and He renders whom He wills barren. Indeed, He is Knowing and Competent."