Can I have a fever and just all thermometers are wrong? And is it ok to have various temp changes? I have high blood pressure but it's well controlled

Fever? Everyone’s thermostat is set differently. Yours might be set lower than most and you have a fever for you but not high enough to be called a fever in most. The only way to figure this out is to do daily body temps every day with the same device and see what shows up. I recommend using a good old mercury thermometer if you can find one. Keep in mouth under tongue 5 min. Or can measure urine temp.
Temps vary. Yes, it is normal for the temperature to go up and down a degree. It's not considered a fever until it is over 100.4. You can feel hot without having a fever.