Whether she's "turning it up" for the internet, or whether she's masking it irl because she knows normal people """wouldn't understand uwu""", is up for debate - and hard to settle without seeing how she behaves in person. It's a weirdly important distinction though. If she's exaggerating for internet clout, then my assessment might swing back towards BPD a bit harder, because that's the kind of attention-seeking, pity-me, look-how-special-I-am shit that cluster Bs thrive on. If she's, instead, worked out that no one else understands her, no one else realises she can actually speak to the dead and do magic, no one gets it, so she has to hide her super special powers in case they come to take her away, the only ones she can trust with the real her are her wonderful understanding internet friends... then yeah, that fully fits with schizophrenia or some other delusional/psychotic disorder.