If your doctors think you are lying, either prove you're right or find new doctors.
I recommend taking one of your home machines in to the doctor's office to compare readings side-by-side. This will help to validate your home readings.
Another issue may be in how they are taking your BP there. You should be sitting in a chair, with your feet on the floor and having rested for a few minutes. Something lik nicotine
or caffeine just before a measurement would also cause a BP spike, but given that you take your BP so regularly, I'm sure you're aware of that. Heck, it could just be driving!