Solved

Fuel stops

Saved the game at a 2 stop 15 lap fuel change and 3 times i went and checked and it changed to 12 laps. Just before race i checked and it said 15 laps.... low and behold in game it changes to 12 laps and makes 3 stops due to not enough fuel

This is due to when the practice laps are done and what the temperature is in context to the race time temperature. The temperature difference leads to over fuelling or under fuelling. Also it can vary due to differrent push levels used during race higher push levels use more fuel. So it helps if you do practice runs in similar temperature to race temperature so best time is just before Qualy or just after race finishes.

Push levels didnt change as i didnt watch race due to being out fuel level was 2.2 so hadnt changed. I saved it at saying 15 laps but went back to change at the defaulted lap change before putiing in laps on a practise runs.