I ran your itinerary thru hauteboy's OneWorld validator.

1: BKK-HKG: 1st of 4 (Asia)
2: HKG-NRT: 2nd of 4 (Asia)
3: NRT-HKG: 3rd of 4 (Asia)
4: HKG-YVR: intercontinental
5: YVR-JFK: 1st of 1 (North America Transcon)
*5: YVR-JFK: 1st of 6 (North America)
6: JFK-SXM: 2nd of 6 (North America)
7: SXM-JFK: 3rd of 6 (North America)
8: JFK-SFO: 2nd of 1 (North America Transcon)
Rule violated!!!! [JFK-SFO] Max 1 segment(s): North America Transcon

I then rechecked it without the YVR stopover.

1: BKK-HKG: 1st of 4 (Asia)
2: HKG-NRT: 2nd of 4 (Asia)
3: NRT-HKG: 3rd of 4 (Asia)
4: HKG-JFK: intercontinental
5: JFK-SXM: 1st of 6 (North America)
6: SXM-JFK: 2nd of 6 (North America)
7: JFK-SFO: 1st of 1 (North America Transcon)
*7: JFK-SFO: 3rd of 6 (North America)
8: SFO-LHR: intercontinental
9: LHR-DXB: 1st of 4 (Europe)
10: DXB-LHR: 2nd of 4 (Europe)
11: LHR-IST: 3rd of 4 (Europe)
12: IST-LHR: 4th of 4 (Europe)
13: LHR-HKG: intercontinental
14: HKG-BKK: 4th of 4 (Asia)
Congratulations!! Valid itinerary!!! - (41119 miles)

It's a terrific tool; I highly recommend it that you use it as you improve your itinerary.