Sf15-
You are 15 years old and wisdom teeth typical come though between 17 years -- unknown age!!!! So one, its unpredictable when wisdom teeth will erupt (come out.) Two, what your dentist is speaking of the domino-effect that could be happening when the last teeth (wisdom teeth) wiggle there way in the arch: wisdom tooth will come down and push on the one next to it, then the pressure will go to the ones further to the tooth next to it, etch
Two issues with that "domino effect" perception A) you can't predict how much wisdom tooth eruption and its direction B) if you have gaps between the FRONT teeth, you cannot rely on wisdom teeth to close and align the spaces.
At the end, talk to your dentist again and set up a consultation ( found a free consult) at your local Orthodontist (Braces Dentist) Best of Luck and let me know if you have any other questions.- AF05