It is my understanding that the zodiac signs come from the measurement of Earth's slow wobble. Supposedly our axis, of planet Earth, is not vertical: it is off by 23.5 degrees.

Our planet makes a circle around this offness, completing a circle in 25,900 years. The zodiac signs come from a measurement of this circle; the circle divided into 12 parts, each part is 2150 years. Did that change? Is the Slow Wobble taking longer? Did the 23.5 degree angle change?

NO, what you were taught is wrong. Surely you are used to that by now?