The last time I went from Luohu to the airport, I had two bags, one on my back and one in my arms. Never again. Also, if I were going direct to the airport, I'd probably choose different transport. I walked across the border and hiked to the Luohu MTR. I say hiked because as I recall, it's a longish walk. Anyway, caught the MTR to Kowloon, stayed there overnight, then caught the Airport Express from the Kowloon station in the morning. The only advantages to this procedure are: (1) the growth and development of back, leg and arm musculature, (2) Kowloon, (3) you can do your flight check in at the Kowloon station and leave your bags there.
All in all, probably not recommended with bags and children. Probably not recommended for adults either. Isn't there a direct ferry from Luohu to the airport?