Actually I have been told by my doctors that Diamox is not the kind of medicine that "builds up in your system" over time, so basically once a dose has been taken and processed through your system, its effects are gone until you take the next dose. Especially if you're taking the tablets vs. the time release capsules. So what she said does kinda make sense ... if you forgot your meds that morning, then the effects of your meds might not show up in your LP results.
However ... that being said, it looks like you've had a bunch of LPs now and you probably weren't off meds for all of those? It doesn't seem like your pressure has fluctuated much over time. LP is such an invasive procedure, very tough for me to recover from ... I can definitely understand your reluctance to do another one. I would talk to her about it, tell her you really don't feel like the Diamox is doing its job for you and you're having a lot of side effects. See if she might be willing to try changing meds, or another approach, without an additional LP given that you've had so little change with Diamox over all this time. Good luck hun!!