the tiredness does pass but just remember when pg you don't have as much engry as before and as you get bigger you can do less
I get at least 8-9hrs sleep a night, eat a good diet, do gentle exercise and take my pg supp elevit. I find all of this helps me and elevit has loads of multi-vits & mins that we require when pg. My OB and GP recommended it in my first pg and I've never looked back.
lots of luck and hope you have more energy soon!