Interesting. It does sound like you may have burned out some of the the neurotransmitter pathways from "overloading the amphetamine circuit" lol, which will impact effects from any releaser or reuptake inhibitor.
Also, just a headsup, the phenidates are all reuptake inhibitors as far as I know. There may be some release activity, but it will be minimal, if at all.
Add to that, many cathinones are reuptake inhibitors, while also being releasers. Some will have more effect on norepi, often resulting in that uneasy tweaker vibe, and the ones with more affinity for dopamine would probably be smoother. Some even have the effect of being a catecholamine transporter blocker as well, which could be another possible contributing factor in inducing psychosis or strange behavior. I should be clear, that many of the modes of action for especially the newer compounds, are not fully known. Some of what is spouted on the forums as fact is just speculation, lots of parroting what others have said with no real data whatsoever. My main point here is that the reasons for a lack of desired effects after "circuit overload" are probably much more complex than releasers vs reuptake inhibition.
3fpm is thought to be a releaser of primarily dopamine, followed by norepi, and a likely negligible effect on serotonin. At low doses of 30-75mg, it is a very functional stim. 100mg and up the euphoria can become more and more pronounced the higher you go. I had a friend take 600 mg his first time, crazy bastard. He said he had the greatest night of his life, and broke his bed having crazy sexytime with his wife. Said he was a little tired after only getting a few hours sleep the next day, that was it. So it is all dose related with this one.
I had an episode at a young n' dumb point in life, where I pushed things way too far with stims. After that I had similar issues to what you describe, and more. Stims didn't seem to work at all, nothing but side effects pronounced. Also had developed some disturbing cognitive issues. I thought I had done permanent damage that I would just have to live with. But if I could do something about it, I would. So for 8 months I had basically no stimulants, no excessive caffeine, nothing that would elevate dopamine, norepi, adrenaline. Along with that I did thorough research with natural and synthetic compounds that show a lot of promise in restoration/protection of the monoamine system. That regimen brought me back nearly 100%. The real success of this process was discovering that the "magic" was back. When I slowly began dipping my toes back in the stim pool, all the therapeutic effects that were once long lost were available to me again. From then on, I took much more of a harm reduction approach, and it has been much more rewarding.
Just wanted to throw that out there in case you might be interested in getting things in the grey matter back to a more normal baseline. As long as excessive dosing is avoided, I think 3fpm would be one of the least offensive rc's in that regard, but you would likely still be supporting the supraphysiological baseline that was set after the brain was flooded with neurotransmitters. A period of abstinence with a targeted approach to restoration did wonders for me. Just a thought.