Craig: that is pretty damn good!
To be honest, I thought you would have difficulty with a 100mm aperture, given that recommendations tend to start at 200mm, or 150mm at a pinch. You surprised me!
Your data looks entirely sufficient to make a scientifically valuable measurement. Don’t worry about the predicted time to be different from your measurement. That is the whole point of the exercise: to test the predictions. Please report it so others can learn from it.
I am impressed, and please keep measuring other transits with either or both of your telescopes.
Paul.
P.S. You should boast about this one in other astronomical fora such as SGL, CN and Bluesky.