I rewrote your itinerary in another form, including the LAX/DFW swap mentioned above (although a direct GUA-LAX service seems to exist according to the OW interactive map):
LHR-BOM//DEL-BKK//HKG-AKL-SCL//EZE-LIM-MEX-DFW-SJO//GUA-DFW-LHR

In this itinerary you'd have:
14 segments (including 4 surface segments) - you can have 2 more
1 flight segment in Asia, None in Southwest Pacific, 1 in South America, 3 in North America, None in Europe - you can add the 2 segments in any continent, since your contingent is still open in all continents

My suggestions for your two segments: DFW-MAD-LHR (if you do not go back to LAX after GUA) and/or HKG-SYD/MEL-AKL and/or EZE-GRU-LIM and/or DFW-MAD-any other city in Europe served by both IB & BA-LHR - many other options open.

Enjoy your journey!