Hi Twinkie50
My pulsing tinnitus first started with my first pregnancy, I really freaked me out, I ended up taking early mat leave just to lessen stress!
I know my dr prescribed me a med to lessen anxiety which I have only taken once (!) as I hate taking meds at all and wanted to find the root cause for the noise as I am sure you do too.
I am assuming the MRI would pick up any tumors, swelling etc am I right?
YOu mentioned that you have a narrower eustacian tube on that side? THere is a condition that children can get that can cause tinnitus it is called otitis media (I think) It may be that the narrow tube is causing this

You metioned slight haering loss at your test in this ear, does your ear ever feel full?
I did a search for pulsatile tinnitus eustachian tube and found some interesting sites