i feel the same and this is my 2nd baby i have a little 2 year old boy.
if your working 80hrs a week thats heeps and looking after your 3 year old! i think you should try to not work as much, take more time to relax is important. just think how tired you'll be when the next baby arrives? so do get some rest now while you can!
i am having lots or migrains aswell like almost every day. it awful.
do you know if your having a boy or girl yet? im only 16 weeks and find out what im having in 2 weeks (i cant wait) im just wondering if the headaches might indicate if its a boy or girl? i had no headaches or migrains last time.
i hope youl find the time to rest, and good luck with it all!