Pregnancy and 24h guard

I need advice or something. These past 2 weeks I've litterally been pulling 24h duty every other day. Im 12 weeks pregnant and its just so tiring! Is the 1st trimester safe to do 24h duty like this constantly? They say regulation states they can make me do duty up until I'm 24 weeks. 😓 I honestly dont know how im doing to do this. Is this safe for my baby? Am I always going to be this tired or just for the 1st trimester? Any advice for staying awake without the use of caffeine?(quit all energy drinks and chain of command wont allow me to drink coffee saying its unhealthy for my baby)😞 Yes, 1st pregnancy. The father is in the field right now.