It absolutely amazes me the complacency that some have regarding MM.
Why would you want to wait until something prompts you to have a second operation? If you waited, something serious may happen that you may not recover fully from as some people on this board can attest to (before they were diagnosed with MM and suffered a major stroke through no fault of their own).
In my case I was lucky not to have a serious stroke but that was enough to prompt immediate surgery and I was advised to get a STA-MCA done so that would be my best chance of immediate blood flow. And then my surgeon told me that getting my other side done was not a necessity but would have to be done at a later stage, but he advised that I should get it done while I was still young enough to recover quickly, so we went ahead within 6 months of my first op, with a STA-MCA on the other side and as it happened they found out that my other side was worse than my initial side, so I was indeed fortunate to have made the decision to go ahead straight away. For me, I didn't want the spectre of possible surgery hanging over my head for years down the track - I wanted to have it sorted straight away so that my health was not in jeopardy. I would never contemplate umming and aahing about this disease, and I am concerned that you are not doing enough about your particular situation. It is not acceptable that you are still having problems 8 months after your surgery - it is obvious to me that something more needs to be done. Don't wait for something to happen as it may be too late then. Why would you want to put yourself at risk?
Call on the professionals that the other members recommend on this board and get someone who is interested in your health and well being and follow through with surgery that is going to improve your situation

My neurosurgeon insisted on a MRI shortly after surgery to see if there were changes and I had to have  an angiogram  6 months after, for him to make sure that the blood was getting through. And he found that it was and everything was working as it should be, and that seems to be  the difference between my specialist and yours by the sound of things.

yup you should check but all depends on what kind of surgery did you have?? if you had the sta then it should have shown more changes if not and you had the edas then you may have to sit tight and be patient.  you should have the other side done soon like moyamoi said it'd be better while you're younger and before you have a stroke to have the other side done. 

i just had my first surgery, edas, done 2/23 and have been recovering very very good, no problem and will be scheduling my next in about 6-8months when i can take the time off from work since i'm self employed.  yes and i could wait, but why wait till i have a stroke or aneurysm before it happens, well just praying that it doesn't happen before i schedule my next one though. 

so again back to your question all depends what kind of surgery you've had.  and yes you should have the other side done, since it is abnormal.

ahh my dr said even at 8 months maybe to premature and he's had patients where on the very 1yr anniversary that his patients have shown great improvement.  just hang in there and hopefully you don't have anymore strokes or tias.  but you should consider having the other side done soon.