Does your soap calculator give the properties of each of the oils for you? On soap calc it would be easy to find a substitute for avocado oil. Many Aussie soapers use rice oils have you worked with that oil?
Here are some of the outstanding numbers for avocado.
Avocado.
Hardness 22
Cleansing 0
Condition 70
Bubbly 0
Creamy 22
RBO Rice Bran Oil a possible substitute
Hardness 26
Cleansing 1
Condition 69
Bubbly 1
Creamy 25
Safflower Oil isn't as hard but you could counter this with coconut oil which is hard
Hardness 7
Cleansing 0
Condition 90
Bubbly 0
Creamy 7
http://www.soapcalc.net/ this calculater let's you compare the properties of all oils that might be available to you.
You will get it with time!
I'm glad you are weighing your items carefully and keeping good notes that way when something does go right or wrong you will have thorough notes to help you decide what went right or wrong! A trail.
My suggestion for the milk soaps is if the water for your recipe is 12 ounces and the lye 6, you can use use say 9 ounces of the water to disolve the lye, and the remaining 3 ounces of liquid use as milk. Add this milk to your batter after the oils and lye have been thoroughly mixed together even at light trace it would be fine as long as you blend it well with a whisk,( not a SB as it will rush the batter perhaps). This soaping thing is an art and science and you too will find your way.