Pluto is only 68% of the size of the Earth's moon. It is only about 2.5 times larger than Ceres, the largest asteroid in our solar system.

A large part of science is refining your understanding as contradictory evidence is found. I used to think Pluto should be a planet, and even met Clyde Tombaugh once, but I have absolutely no concerns about Pluto being reclassified as a dwarf planet. It is just a label and our understanding evolves.