Did you do the second skooma quest, the one that sends you to a location outside the city? If so, you are done with those.
However unlike other Jarls, Jarl Laila does not bring up the whole "buy a house, become my Thane" thing until you've met ALL the requirements for buying Honeyside and becoming Thane, which includes the skooma quests and the necessary favors for hold residents. In the major cities like Riften you have to do five favors, not three. You're still two favors short.