Okay let's talk about essential oils for a minute. First you need to understand that essential oils were originally developed for health, they are in actuality over the counter drugs and must be treated with the same respect. Some essential oils have more contra-indicators than others so know what it is you are handling.
Now let's look at safe levels of essential oils. Unlike their fragrance counterparts you should not go over 3% total eo or you move into therapeutic levels. You also should have warnings on your labels as to what contra-indicators there are for the oils you've used. You also need to keep in mind that the molecules of essential oils are so small that they bypass the blood brain barrier as well as the placental barrier for pregnant women. When training as an aromatherapist you learn how each oil affects different organs, and believe me when I tell you they do affect the organs, it's not just a feel good memory association thing. It is very real.
Here's an experiment for you to do. Take come garlic and run it on the soles of your feet, within 20 minutes you will have garlic on your breath and you will be able to taste it. Neat trick, but it certainly demonstrates how essential oils move through our body.
Sorry for the long post, but it is just so important to know what you are working with.
To anchor essential oils that are highly volatile, like citrus, you can use clay. Mix your EO's into a clay, hydrate the clay so it's not pulling moisture out of your soap batter and at trace, mix this in. Something else that helps anchor citrus is Litsea Cubea (May Chang) as well as Lemon Grass.