Social anxiety/disassociation as the week progresses

Hi guys, I have a curious question about my Vyvanse side effects. Without changing my dose throughout the week, I see my side effects getting progressively worse (social anxiety and disassociation). On Monday I’m perfectly fine, friendly and competent and by Friday I’m withdrawn, disassociating, and kind of a mess.
If Vyvanse is only in our system for up to 12 hours I’m not sure why these effects would compound like this. My psychiatrist couldn’t explain it so I thought I’d ask all of you. Thanks so much!