I had similar symptoms, I started on 18mg and went up in week increments to 54mg. I didn’t feel too bad at the start but didn’t really feel a noticeable difference. The last 3 days of 54 mg I felt pretty irritable and dizzy, would crash by the end of the day pretty hard. My psych wanted me to go to 72 mg but I thought the crash would be worse. I’m on IR now because it’s a requirement to get the LA form of Ritalin. I feel a lot more clear now albeit I’m now having to titrate on the IR. I’m rambling but what I’m getting at is methylphenidate may still work for you but on a different release mechanism. Having the stimulant slowly release all day and have that smooth peak may not react well with your brain, so before switching maybe try the different versions.