Shakes, dizziness and constant hunger are generally signs of hypoglycemia, so it may have been that your body wasn't getting enough calories. I know how scary blood sugar episodes are, so I'm sorry that happened.
I found that until I ate really regularly with small meals throughout the day, that feeling didn't pass.
I was on met for between 13 and 14 months before it started working for me. My insulin always came back borderline/normal, so i never showed IR in my labs either. But more studies are showing that insulin labs are usually inaccurate at best. Often the tests are not sensitive enough to pick up IR in most women, so they say that met should be given when symptoms dictate...particularly high male hormone and absent periods. Take a look at the FAQ thread for more info on that if you'd like to see the studies.
One other aspect that really changed how my body handled met was a really concious change in my exercise/diet. I had been a pretty sporatic exerciser up to that time, and after I started really conciously fitting in aerobic exercise for at least 35 mins and changed how i ate so that my diet wasn't counter-acting the drug (via the Insulin resistant diet), it was like a switch was flipped for me. For over a year the met had done little to my labs, my periods were still irregular at best and I couldn't lose weight very easily. After that, The weight came off a little more regularly (~3 pounds per month or so for 2.5 years - I lost a total of 60 pounds) and my labs started to really improve (testosterone, free androgen, and even my insulin lowered slightly too, showing where i was was not normal for me). I realize now that met doesn't work all that great by itself...and in conjuntion with diet and exercise it's like a new drug. I encourage you to try those aspects if you haven't already.
There are other meds like actos or avandia that might be helpful if Met just isn't right for you. Some ladies also find that switching from Gluc to generic Metformin or the Extended release version seems to qwork better in their individual situation. The Dr's say that there is no difference between them, but some ladies swear different versions of the drug help more with less side effects. Definetly talk to your Dr about these other options.
Hope you can find the right combination to help you.
All the best!
Glucophage 
As i need to lose abuot 40 lbs i thougth it best to steer clear of this one. just thought i'd drop a line and let you know in case you didn't already.
