I’m on generic Vyvanse and have had a similar experience to you. I went up to 40mg but didn’t notice that much of a difference to the 20mg, so I asked to go back down. We added a regular short acting Adderall 5mg booster to go along with the 20s. That combo seems to work relatively well for me, but I think the long-acting Concerta + 5mg booster was the best fit in relatively recent meds history. I switched about 2 years ago to Vyvanse because it was very hard to find the correct Concerta ER dose in stock consistently at my pharmacy .