When that happened to me, I simply wrote down all the predictions on paper right after the visit, literally word for word. Then six months or a year later I reread it and realized: half the predictions were so vague that they basically match any life. And the other half - I'd forgotten them, and when I "remembered" some event, it didn't match what was actually said.
So here's what helps tell real coincidence from illusion. Get a record of the predictions (or write down what you remember now) and assess how specific it actually was. "A new person will come" - that means nothing, people come all the time. But "in August 2026 you'll get a cat" - that's actually verifiable. Second thing: did you remember this prediction when the event happened, or did you remember it after the fact? If you remembered it only after the event, that's a textbook case of false memory. Third - check whether any of the things the psychic predicted accurately and specifically came true, but you forgot about. If not, then probably the coincidences aren't real at all.
The main thing is don't rate the psychic based on two or three matches with vague phrases. If one out of ten predictions came true, that's just the statistics of random chance.