I still think you need some fast acting insulin, Heather! I would really stress this to your doctor! The Mix isn't going to help you with random highs! For now, TRY not to stress over it! Easier said than done, I know!!

If you're having an issue with insulin resistance, I'm not sure there's anything that can be done. I don't think preggy mum's can take Metformn. I'm not positive on that note, though!
Don't worry too much about the size of the babies. My mother in law, had twin boys (my hubby's one of them) she's a wee little thing. BOTH boys were over 7 lbs. each!!!! This was back in 1961 too! And NO C-section, either!! Vaginal birth, both of them!! No, she wasn't diabetic at the time (though she is T2 now), but still. To even carry twins full term, and have them BOTH weigh what a single birth baby does, is amazing to me! It can be done!!
As for me, I'm a wee one too -though the body has hidden that fact for years now! LOL I do have a very small frame though. I managed to have an 8 lb. 6 oz. boy, in just over one hour at that, and I was NOT diabetic at that time. Vaginally and NO meds, whatsoever!! He was my easiest to have. He was my second baby.
My daughter, I had GD, and she weighed 7 lb. 14oz. Vaginally as well, and only some pain meds in the middle of labor. By the time delivery came, actually about 1.5 hours before it came, I had NO meds whatsoever in me!
Funny thing is, my first one, he was my smallest at 6 lb. 9 oz. and I SWEAR he was trying to kill me! LOL Labor for 3 days, NO kidding!! Still again, NO meds, except some Demerol, which did NOTHING for my pain, but did allow me to get some sleep in between contractions! And dream some VERY vivid dreams in those 2 to 3 minute spans! LOL
I MADE my husband (at the time) SWEAR to me that he'd NEVER get me pregnant EVER again. Guess what? Two and a half months later, I was pregnant with "the big one"! LOLOL
I think you'll be fine, no matter the size of the babies. They are MUCH better equipped to deal with these things these days!
The most important thing, is their health!!