Hi there. So, one sign that you have anxiety is the constant checking of your BP. That constant need to check is health anxiety and irrational. You've been given the all clear, correct? Doctors take an oath to 'do no harm' and while they miss things, if there was any cause for true concern, they'd dig deeper most likely. Or your parents would as I'm sure you've talked to them about it. We get ourselves into further anxiety when we try to be our own doctor. :>) I say that with kindness as I understand health anxiety, I have it sometimes too. So, what do your parents think of the spikes? Not all home equipment or wear-ables are accurate and yes, our anxiety level can affect our blood pressure. Our parasympthetic system will react. SO, since you are being told anxiety is very likely the cause, you should begin to work on that. Therapist? CBT therapty is excellent. And if it is not the cause, you aren't doing yourself any harm as you work on the root cause.
Please read this: https://www.mayoclinic.org/diseases-conditions/high-blood-pressure/expert-answers/anxiety/faq-20058549 It is from the Mayo Clinic. It states that-- Anxiety doesn't cause long-term high blood pressure (hypertension). But episodes of anxiety can cause dramatic, temporary spikes in your blood pressure.
Talk to your doctor about this. let us know what you think
Try meditation with apps like calm and see if that helps.