Honestly, the things people do..I think you should let your doctor treat you. The buzz disappears, and as dose increases, regardless of tolerance and effects on mood, so do the incidence of negative side effects increase. A good 15% of people that become psychotic under the influence of stimulants do not entirely return without residual effects. This is how people get forced onto antipyschotics. I realize you're not at that point right now, given that you're telling the truth, but this is what lies in the non-too-distant future if you keep trying to cop a buzz off of medication. Stimulants in particular are known, if continuously abused, to send one down to the dregs of society particularly fast. Faster than you think possible...
But, heck, caffeine up until ~300-500 mg for the tolerant is generally safe. Why not have a few cups? That's if the last 90 years of use mean anything.
But yeah it sounds like you need some nutritious food and a good rest. If you're depressed or anxious or whatever, let your doctor know so that they can prescribe a more advanced medication that can actually trick your brain into acting as prescribed without having to keep on raising the dose forever.
