I assume you mean 20-25mg, as 0.25mg of MDMA would be less than a microdose
Well you're not likely to end up tied to a bed or get serotonin syndrome, but you should anticipate the trip to be less pleasurable as the purpose of your antipsychotic is to block/modify the activity of a whole bunch of receptors that MDMA would normally act upon.
I would suggest you don't just take more MDMA to try and overcome the antipsychotic though, as you really don't know how you'll react unless you've done so before. And as I said before, you do risk causing an abrupt and unpredictable aggravation of your underlying mental health disorders. So tread carefully.