Travel - flying

For our anniversary we planned a trip to London and we are staying in India a few days to attend a friends wedding. The flight to London from Dallas is about 9 hours, but the flight from India back to the US is 16 hours non-stop. Both long flights are over night flights and we have to sleep otherwise we will be miserable. I'm still struggling with morning sickness (all day nausea) and I'm at 13 weeks. I will be about 15-16 weeks when we are gone. Any tips on making sure I'm not throwing up on the plane and can get some sleep without getting any blood clots or swollen feet?!