I am a 27 year old female, 140 lbs with a slim neck and can see my right neck vein pulsing (not my left) anytime i lie down. my echo, carotid ultrasound and ecg were normal. should i run more tests?

The carotid artery is a large artery & I'm sure that's what you see pulsating. A normal carotid ultrasound is very reassuring. I assume you don't have high blood pressure which could accentuate carotid artery pulsations. If you still have concerns, consult a vascular surgeon.

Visible venous pulsations in the recumbent position is not abnormal. A normal echocardiogram and ECG although not necessary to answer your question are reassuring. Don't know why a carotid ultrasound was done. You do not need more testing! Be reassured.