If you are prone to being psychotic and skip your anti-psychotic meds, you will be even more prone to being psychotic during those few days. There could be some rebound dopamine receptor sensitization when you cease anti-psychotics, I'm not sure if I'm naming it properly but I'll explain briefly what I'm after. When you take certain antipsych meds, they kind of numb a lot of receptors (esp. dopamine) in your brain. When you suddenly stop taking your meds abruptly, they won't be blocking your dopamine receptors and numbing them anymore. You have just opened the gates for receptors that haven't had really had any proper action for a long time, they can be extra sensitive to other stuff than the anti-psych meds that were blocking them. Now imagine being schizotypical, having this happen and then taking LSD. It could be a real recipe for disaster.
I have little personal experience with zyprexa, but for example seroquel (quetiapine) at anti-psychotic doses caused me to go really hyper and euphoric if I skipped my daily dose, my brain was going way faster than normal. Tapering your dosage down before stopping could prevent this, but you were talking about simply skipping your meds for a few days. As you can probably see, this is a bad idea even without the LSD hehe. I don't recommend LSD to you, but if you insist on taking the risk, you should atleast do it at a time when you don't need any meds at all. Don't be impatient, you've got years of life ahead and perhaps one day you find yourself in a situation where taking LSD feels safe. Why risk it all at young age? I mean you could find yourself incapable of getting a job if you fry your psyche right after graduating... Maybe it's nothing permanent, maybe you'll just end up wasting a few years at your best age as a psych patient zombie thingy on neuroleptics, or maybe you'll be just fine after you take LSD. We don't know for sure anything but that you're part of a risk group and the risks are very real to you.