In your situation I would probably take a cab or DiDi to PVG, but given your preference to avoid cars, just take one from one terminal to the other. It will cost virtually nothing and given the short distance your chances of having something bad happen to you are extremely small. (I’d argue they’re rather small anyway, having taken a great many taxis in China and lived to tell the tale, but a guy did once fall asleep while driving me to PVG. That happened to me in Germany once too though.)