From my quick look, you have a lot of problems:

xit SFO No direct Flights to UIO
UIO (1)
EZE (2/1)
GRU (3/2)
overland (there do not seem to be any connecting flights) to
GIG (4) No Direct Flights to CDG
CDG (5) No Direct Flights to CAS
CAS (6/1) No Direct flights to TLV
TLV (7/2)
overland to
IST (8)
BUD (9/3)
DBV (10/4)
overland to
CDG (11) No Direct Flight to BKK
BKK (12) No Direct Flight to DPS
DPS (13/1) No Direct Flight to DPS
DEL (14/2)
HKK (15/3) I assume you meant HKG.
PER (16)
SYD (17/1)
AKL (18/2)
PPT (19/3) You cannot get to PPT on a *ONE* Ticket
SFO (20)

Okay....
All those places where I said "No Direct Flight" means you have to have a connection, which means TWO segments to reach the next city. That puts you several segments over your limit of 20. You may be looking at some codeshare flights for the end of your trip, like PPT. If you want to fly American Eagle, as part of American Airlines, you can do that. However, the PPT routes you probably saw are Qantas codeshare with Air Tahiti Nui. Those flights are not included/allowed on a *ONE* ticket. Have you gone to www.oneworld.com and clicked on the "Interactive Map" on the right. Only flight paths in Blue or Grey are allowed on a *ONE* ticket. You'll notice LAN flies to PPT via IPC and SCL. The problem is that PPT to either IPC or SCL is a transoceanic flight, and you're only allowed one of those. So, once you get to PPT from IPC or SCL, you have to keep going westward, but you would be breaking the rules (two transpacific flight) to then go back to IPC or SCL in an attempt to catch a continuing westward connection. The only way to reach PPT as part of a *ONE* is to buy a separate ticket.