Oh I see what’s happening: In step 3. you’re actually traveling much faster than you’re expecting.
If you set 250kts as your decent speed that’s your IAS. Your true airspeed will vary throughout the decent. It will be higher than 250kts until you get to 0 MSL. That’s why you’re traveling faster than you anticipated and are overshooting the airport.
I recommend just using the ETE dest and the vertical speed that coincides. Then this effect will occur in reverse and you’ll undershoot which is a lot more desirable. Let me know if this wasn’t clear! 🦅