Hi Andy,
As you have found, no matter how badly and fast you want off this med, your nervous system has other things to say about it.
Your taper was way too fast. Each time you cut, it was 50% as far as your nervous system was concerned. On top of that, your system never had a chance to do the remodeling, up-regulation of serotonin receptors, it needed to do before you challenged it with yet another 50% cut.
It takes four days for a new dosage to become steady state in the blood, and then another couple of weeks for the body to respond to this new level of drug, by hopefully up-regulating in the case of reducing the drug. Then, you need another week of stabilizing at this new level before challenging your system with another cut.
Bigger cuts lead to bigger destabilization and withdrawal symptoms. The bigger the cut, the longer it takes for the system to make the adjustments. The withdrawal community has found 10% to be the least-harm approach for most people. About the fastest you can go is 10% every three weeks. At this rate, the disruption is so small for most that they hardly feel any withdrawal at all, and so can go on living without losing functionality.
I think you are thinking that at 10% you would be feeling horrible the whole time, but that is not the case.
You can't force this to go faster by cutting bigger and more often; it just doesn't work that way and that is so many people fail, go back on, fail again, etc. So much more time is wasted doing that compared to just doing the 10% when you are stable and only continuing cutting when you are feeling stable. Never cut on top of withdrawal symptoms!
Your system has been through a lot and so you should stabilize on your reinstatement dose for at least a month before trying again; tapering too soon could make even the 10% taper fail.
Lots of us are making liquid mirt if we can't get ahold of the liquid version from the doc. Mirt doesn't go into solution very well, so you need to be sure to shake well right before measuring with an oral syringe. Evergreen on this forum made a liquid mirt solution using half water and half syrup to help suspend the mirt.
Mirt gets very difficult to taper at the low end under 7.5 mg. This is because even small cuts lead to a proportionately larger number of receptors being freed up by the drug, along with the need for the nervous system to up-regulate (add more receptors), so lots of destabilization.
If you make a cut and bigger symptoms develop than you can handle, up-dose to the previous dose, stabilize and then try a smaller cut. You really need to listen to your body in this process.