I have one week left in my pregnancy and I have to say that thankfully Tri. 3 got a lot better. I was so sick and EXHAUSTED the first 2 tri's. I have a 2.5 year old girl who is a very good girl...I can't imagine 2 littles running around!
Obviously, talk to your doctor. Mine actually told me to drink a little bit of caffiene daily to help with the energy and the bad headaches I was getting.
Napping has also helped me, but I only have one little one at home.
And finally, LET THE HOUSEWORK GO! I made the deal with my husband that I would clean everything that was waist high and he got everything below that. He works full time and has a commute, so sometimes the house doesn't get put back together until the weekends, but it is what it is! I've been nesting lately, so I've naturally had small boosts of energy to pick up a few things and keep them clean. The playroom however, gets trashed daily and my hubby picks it up every few days.
Hopefully, Tri 3 goes better for you since you've struggled already so much. Best wishes and a giant HUG.