Good to hear from you Malisa, how are you doing?
That's a good question (about the calories). As far as I know, both oils are low fat and very high in nutritional value:
Based on a 2000 Calorie a day diet ...
Flax Seed Oil cantain about 25 Calories with a total fat content of 3g which is 5% of DV -- this is based on 3 softgels per serving.
Evening Primrose contain about 10 Calories from fat with a total fat content of 1.5g which is 2%DV -- this is based on 1 capsule per serving.
Fish Oil (omega 3 & 6 oils) are about 20 Calories from fat with the total fat 2g or 3% DV. Saturated Fat is .5g with a 2%DV -- this is for 2 capsules per serving.
These amounts may vary depending on the brand you buy, or if you take it in capsule form or the oil itself. You should be able to see the nutritional values on the packaging of the product.
About the compatibility. Both Flax Seed Oil, Evening Primrose Oil and Fish Oil are what is known as "Polyunsaturated Fatty Acids" -- the only difference is that the first two are plant based and the other animal based.
I don't think it matters if you combine the two (flax and EP Oil) just keep note of the %DV you are supposed to take so that you don't overdose when combining them.
Personally, I would stick with the Fish Oil and Flax Seed Oil as these two particular oils have far more benefits and nutrient value than Evening Primrose Oil.
Hope this info helps ...