For past 7 months, i have been unusually more fatigued. i get 9hrs of sleep but i drag during the day. i'm 18

Fatigue: Need a sleep study to rule out sleep apnea as well blood work to make sure nothing medical is causing the fatigue. Suggest you see a PCP or sleep doc.

Most likely nothing: I believe you are quite lean and that is why your aortic pulsation is visible. If you are concerned about a possible aneurysm (ballooning of the aorta) a simple ultrasound should be able to set your mind at rest. I am assuming no other symptoms.

See a good doctor: There are many possible causes of fatigue. It's impossible to diagnose you here: you need an exam and tests. Possible causes include anemia, thyroid and other hormonal imbalances, vitamin/mineral/amino acid deficiencies, all sorts of chronic infections (viral, bacterial, fungal, parasitic), environmental or food allergies, environmental toxins, sleep apnea,stress etc. Please see an integrative Dr.