First another minor correction In line 1, "JHB" should be replaced with "JNB"

Note some of your segments, do not have a first class cabin, specifically:
All the RJ flights (LHR-AMM-ISU-xAMM-LHR)
The three flights from SIN to PEK

The AMM-ISU-AMM is not likely to be the best use of two segments (either cost or mileage) and I also seem to remember that flight two/from Iraq are not eligible for AA mileage.

As Gardyloo suggested, starting in AMM might save you money and segments that can be used elsewhere.