Chinese Visa Question

Hi,

I am a Canadian English Teacher working in Korea. I have a trip booked to Beijing for 2 days in August, however my ARC Card expires in 4 months... so I can't apply for a visa.

However, I read online that if I have travelled to China within the past 2 years, I can still apply for it regardless of how long I have left on my ARC Card.
I had a layover in Beijing last December ( 7 months ago) . I did not leave the Beijing airport but I do have a Chinese stamp in my passport. Would this qualify me to apply for application??

Also, I will only be in Beijing for 48 hours... but my flight schedule is Incheon>Guangzhou>Ho Chi Minh City ... then Siem Reap> Guangzhou > Incheon... because I have a stopover in Guangzhou first.. does this make it a domestic flight to Beijing so that I cannot have a 72 hour free transit?

Any help would be appreciated!! im desperate!

Thank you in advance