They definitely make 1cc/100u syringes with 31g 8mm needles… I used to use them when I was pregnant 
Insulin syringes come in three sizes (30u, 50u, and 100u)… the various needle gauges and lengths are available on any of them… bigger volume in the syringe doesn’t mean a bigger needle.
I think it might do you some good to see an Endo… they may have some different strategies to manage your IR more effectively… pumping may not help with the amount of insulin you use (you’d be refilling daily), but it’s hard to say for sure.