18F High Blood Pressure ?

**I am 18F, I weigh 112 lbs/50.8kg, and I am 5'4/162.56cm. I take 30mg Vyvanse for ADHD and 1mg Guanfacine for sleep. I don't take any other medications.** **I don't drink. I don't smoke (weed or cigarettes/vapes). I don't take any drugs orally or otherwise (except my prescribed medication). I don't take any vitamins except 2.5mg of melatonin at night for sleep.** Other possibly pertinent information is that my family has a history of abnormal blood pressure, but *only* later in life, like when they are/were in their late 40s-70s (my mom has low blood pressure, my grandma had high blood pressure, and my great grandma had high blood pressure). I also have a pretty unhealthy diet with a lot of highly processed foods, mostly sweet foods like candies and cakes (but not a lot of salt, which I know is a risk factor for high blood pressure). Basically, about a week ago, I went to a plasma donation center to donate blood, and they told me that my diastolic pressure was elevated to 108. They re-tested 10 minutes later, and it was even higher (120). I don't know what my systolic pressure was, but it was in a normal range. I re-took it at a CVS blood pressure machine 3 times in quick succession today, and I got: 142/93 124/84 123/78 (in that order) Importantly, I did have caffeine today, which could've raised it and I took my ADHD medication. I'm planning to make a Dr's appt, but I have to wait till tomorrow because they're closed already for today. Any ideas why my BP is high? I feel like I'm really young for high blood pressure. So I'm trying to figure out what could be going on here.