Hi i am 18 years old, i think i might have postural orthostatic tachycardia syndrome i am not sure and not wanting to self-diagnose myself.. my heart rate goes up by 30-40 beats when i go from sitting/ laying down to standing up?

You certainly have met one criterion for the diagnosis if your heart rate rises by over 30 beats. We don't know what happens to your blood pressure , how long the rapid heart rate lasts or what symptoms you experience. POTS is.more common in young females & there are treatments for it. Consult a cardiologist for evaluation,advice,treatment & followup.