If you can wait one more month then better to exclude the month of July as was in number 1 and just rely from Aug - Jan. If these wages figures are also including the overtime then you need to isolate it from the base salary to get it calculated by none-salaried person formula (total amount of overtime from the last 6 months /6×12= ??). Afterwards, add the resultant figure into the base salary where the lowest wage figure during the last 6 months will be multiplied by 12. Consequentially, that will be the correct annual figure for the purposes of meeting the financial threshold.
*** I know what you are trying and few others might say to use the whole income under none-salaried person method where based on above figures you can conveniently meet the requirement. But unless the caseworker won't notice that you actually have a base salary despite working varying overtime, it won't succeed as per the official guidance which quote I have given you earlier. In this relation, what I will recommend you to do is to start undertaking excessive hours of overtime***