Could my 3 year old band have a leak & what may have caused this? I've had many 3 monthly fills to reach any restriction.

If you are only getting 2ml after several fills this means there is most likely a leak in the system.  The fact that the fluid looks yellow also suggests that the band, port or catheter has been compromised.  In my experience the most common site of leakage is usually from the port.  Consult with your bariatric surgeon.  You may need to have the port replaced.   

Based on the symptoms you are describing, there is probably a leak somewhere in the system.  When the port is accessed for a fluid check, the amount inside should be the sum total of what has been added up to that point.  To have 2ml after multiple adjustments is highly suspicious for a leak.  Since your port is difficult to access and it has been jabbed multiple times without success, The ports silicone seal may have developed a small leak.   Seems like a good opportunity for your surgeon to revise your port so it can be exchanged for a new one (which will be undamaged) that can be placed more superficially so access during adjustments is not so much of an ordeal.   If the leak persists after a port exchange, then you know the problem is in the band proper and you will need to have the entire thing replaced.   If your surgeon keeps ignoring the signs and manages the problem with frequent "refilling" I would recommend that you seek a second opinion.  Don't give up hope!!  Good luck.