Travelling when pregnant

Hi everyone! Has anyone travelled multiple flights during a trip when 20+ weeks pregnant? I'm going for a holiday and heading to 3 countries all by which i need to take a plane multiple times over a period of 18 days. The flight to and from SG is quite long about 12 hours but between the other countries it takes abt 2-3 hours. Total will be taking 6 flights altogether. I can't change the name on the flight ticket and if i don't go, its thousands thousands of dollars wasted. Gynae did not say I couldn't go but am just thinking what to do. For my own mental well being, i really want to go for one last trip before baby is born but if anything were to happen due to the multiple flights or anything happens overseas, i will also regret. Am at such a loss and any advice will be greatly appreciated.