While many moms experience pretty extreme fatigue in early pregnancy--the first trimester can be like there's an invisible switch inside you that suddenly sends all your energy to your uterus, I swear!--the fact that you report feeling dizzy and near blacking out when you stand makes me concerned. Those are very clear early diagnostic signs of anemia, which is also common in pregnancy. Another way to check is to press on your thumbnail. It should go white underneath as all the blood gets pushed out of the tissue under it. Then release it and watch for how quickly it pinks up again. It should be practically instantaneous. If it seems to take a few seconds, that's another sign of anemia.
Your midwife or doctor can order a simple blood test to check, but be aware that often a standard iron supplement doesn't really help all that much. Most iron supplements actually are nothing more than industrial rust waste, and believe it or not, that comes from government subsidies of industry.
The reason many mothers get anemic during pregnancy is because there is a huge increase in blood volume, and much of that happens in early pregnancy as you are building a placenta and a complete new circulatory system, while also increasing your own blood volume dramatically to carry nutrients and oxygen to both baby and you.
Your focus should be on building healthy blood cells overall and also getting plenty of fluids to help this process. My midwife--who I also trained with for awhile--tells all her clients to eat 7 fresh young dandelion leaves each day to keep healthy. Dandelion is a great liver tonic and blood generator, and far from being a noxious weed, was actually NOT NATIVE to the Americas but was brought over intentionally by the English wives on the Mayflower. They knew it's value for getting through nutritionally deprived times and did not know what they might find in the New World--they also brought stinging nettles, which are an excellent source of nutrition in pregnancy also. In Great Britain, many families would protect their nettles patch and pass it down from generation to generation for it's nutritional value. With dandelion leaves, make sure they are not sprayed with any week killers, or, um, any dog liquids. Pick the young fresh leaves, and add them to a salad or a juicer blend.
Another good blood iron booster is Yellow Dock. You can find the dried powder in herb stores, and put it in capsules yourself, or you can purchase capsules ready made.
Finally, increase your intake of spinach, kale, chard, beet greens, collards and any other dark leafy greens you might like. If you don't like them much, try steaming them and adding them to lasagna, mixed in with the ricotta cheese. You'll hardly notice they are there!
Any iron supplementation should also include vitamin B-12, which helps you absorb whatever iron you do get. Many times I've seen women not make much progress in anemia with iron supplementation alone, but when they add B-12 to the mix, they start feeling better and their hematocrit and hemaglobin counts go up. Get a good sublingual (under the tongue) version, as B-12 is difficult to absorb through the normal digestive process but has receptor sites directly under the tongue.
Definitely get this checked out, because anemia in pregnancy can develop into serious issues.