increase dose?

Hi, i’m currently on 30mg of vyvanse. I started on 20mg and immediately noticed that the medication doesn’t last as long as it should. i try to get adequate sleep, and eat high protein. on 20mg my medication would only last me 5 hours, then i’d crash and take a nap in the afternoon and still sleep at my normal schedule. i’m experiencing this same problem on 30mg, however, after the 5 hours i just don’t feel motivated or productive anymore, and whenever i try to do homework or study i feel the same as i normally would unmedicated, but i feel the physical effects of the vyvanse still. I have an elevated heart rate and don’t feel physically tired. Just unmotivated and don’t want to do anything other than bed rot and doomscroll on my phone. Not sure what i should do at this point. Should i try a different medication or go up my dose? would that help with the longevity of this medication?