Hi M.!
You described my experience perfectly! I was fine until I had my first pregnancy. My body will not absorb iron, no matter how much I take, so I am tired all the time. In addition to that, the doctor said "my brain does not record sleep" so that is why it feels like bedtime as soon as I get up. Over the years, things I have found to help:
1.) First thing in the morning, eat a banana, oats, water or juice and take B12 tablet. A few hours later, eat sugar. (Two cookies, cupcake or a handful of raisins, etc. Fruit is obviously better than cookies and icecream, but I usually eat a Quaker Chewy Granola Bar with choc. chips...sometime two of them.
2.) Eat raw green with lunch. Romaine, spinach, celery, peppers, etc. Eat any lunch, just be sure to eat raw green too.
3.) Snack sweet every few hours as above. (Just two cookies!)A hard boiled egg along with those cookies is really energy boosting!
4.) Eat beef everyday. Yep! Those were my doctor's orders! As long as you eat oats and veggies, meat is not a problem. I feel my best when I have a lean steak...about the size of the palm of my hand, not my whole hand size.
5.) As your kids grow older, have "Quiet Time" for everyone in the house three times a day! Mid morning, I would snuggle and read with the kids in the *fancy* living room for a long hour. Then they would go play in the family room again, and I could sometimes lie half alseep for awhile. After lunch, all kids go to their beds with books. They don't have to sleep, but the usually will. An hour before bed, it is bathtime, then snuggle in bed and read stories. After lying down to read then I could be up awhile longer in the evening.
6.) No nutrasweet, aspartaime, sweet and low, equal, splenda, etc. SUGAR only! Those chemicals cause A.D.D. and cause major brain drain leaving you so tired. Sugar has 15 cal. a tsp., is natural, and of course, contains no fat or chemicals. It is a great thing! Honey is even better, but I don't like it. Working on it though.
7.) The fewer chemical preservatives (frozen and convenience foods) that you use, the more energy you will have. Grow tomatoes in a pot or garden.
8.) Jumping around exercise wears me out. Simple slow strength maneuvers give me energy.
9.) Once the kids were older, coffee became a wonderful thing in my life. I make it weak so I can have it along with my sweet snack every few hours. The doctor also prescribed Wellbutrin which helps a great deal. (My sisters hated taking it for this same problem and just use coffee.)
10.) Deep breath excercise a good stretch every hour.
Hope this helps!