As for the task, it's probably the new one for Natalie. If not, just go through with them from the get-go. Might have missed one by accident. They are 37 in total. The one object you're missing is probably the secret one from the achievements? If so, on the weekends you can dance with Mia in your room if you have the CD. Do that 4 times.
Other than that, I am also stuck on 114/116, I can't seem to find the other two events at all, no matter where I explore at what time.