Usa-shanghai- macau- hong kong - beijing - usa

shanghai mach17 to march 20 fly to macau march 20 take ferry to hong kong mach 22. Fly hk to beijing march 26 then return to us march 30 Do i need visa or i can opt for the 144 free programme twice? I heard horror stories where people was confident that could fly no visa and then check in agent does not allow boarding. I am flying aircanada to shanghai , juneayao air from shanghai to macao. Macau to hk via ferry Hk to beijing in airchina then beijing to us back in aircanada.