Did you have a test for anti-GAD 3 times or do you mean they tested blood for different antibodies and you tested positive for one of the antibodies?
Have you had a second C-peptide test recently to see how your insulin production is now?
I've had a diabetes diagnosis for close to 3 years now and have been on insulin since a month after diagnosis. I don't have a straight forward diagnosis even now, even though my specialist and I have decided to go with the assumption I'm T1 (LADA). That only happened at the beginning of this year, over 2 years after my initial diagnosis, and it didn't change my treatment. I'm fine with that, as my treatment works well.
Not to say you shouldn't try to find out what kind of diabetes you have, only to show that good treatment is possible even without a definite diagnosis.
Good luck, and let us know how you get on!