Looking for perspective, how do I know if my dose is correct?

I just recently started taking generic vyvanse. I noted an immediate change at 20mg. I was happier, more productive, less distracted, no depression, etc. Of course, after about 2 weeks or so my symptoms started to return, so I got an increase to 30. After a month I experienced the same and got bumped to 40. Two months into the 40mg and I am starting to feel like it isnt working.
One of my go-to avoidance routines is doom scrolling or internet surfing for light porn. I have noted that during the past week I am almost compelled to jump on the computer and start searching or scrolling through Lemmy.
I am just wondering if this is a normal progression. At what point does the increasing of dosage stop?
Gotta throw in that I started gabapentin for my anxiety this weekend too, and not sure that is helping or hurting.
Overall, I am just really feeling confused. I am not sure I trust my own assessment of the effect of the meds. This is a lonely place because I dont have anyone around me with experience regarding ADHD medications, so any input is greatly appreciated.