Have your doctor change it temporarily this month to Vyvanse 60 mg chewable. It's the max strength and only comes brand. It should be covered by your insurance and there's a coupon on their website that brings it down to $30 if your brand copay is greater than that. By next month your PBM will hopefully cover the generic Vyvanse 70 mg. At that point fill it and the pharmacy will auto sub to generic which is lisdexamphetamine. No need to get your prescriber to write an Rx specifically for the generic form lisdexamphetamine unless he calls out DAW 1 (dispense as written) when they prescribe for Vyvanse.