rant about formula!

I decided to switch to formula after breastfeeding wasn't going well. my baby was losing too much weight. so I made the switch. I feel good about it.
the one thing I don't like is that there are not clear ways on how to make the formula. I know the powder is not sterile. on the formula can it says to use boiling water if your baby was premature or has an immune disorder. on the website it says to use boiling water and let it cool to room temp before adding the powder. WIC says to not wait more than 10 minutes after boiling to add the powder to kill bacteria.
and they also said that you only need to do this until 4 months of age. WIC says to not store the scoop in with the powder but the formula company says to store it in the container. 
my mom is taking a lactation consultant course to be certified. they talked about formula yesterday. she found out that you must always boil and mix powder while it's hot no matter how old the baby is. and also the measurements on the plastic bottles are not accurate and to always use a glass measuring cup because they are most accurate. I tested it out last night and my bottles are a little over half ounce off! and my mixing pitcher is off too! so was I diluting my babies formula before?? I feel like I was. and that makes me feel horrible. that's not healthy for a baby! 
I always felt like I was unsure about making it correctly even though I followed directions and guidelines. but still felt nervous. and I don't like that because it has to do with my babies health. I boil the water and wait almost 10minutes and then pour in my powder that I premeasured out. but I usually use the measurements that are on the plastic bottles and dr brown pitcher I use to make about 6 bottles at a time. 
it makes me alittle mad at these companies for a: not being on the same page about how to correctly mix the formula. b: not having the measurements be the same on glass and plastic. and c: I feel like this shouldn't be feeling like an experiment! this is my babies health and other babies. all this information should be general knowledge for formula fed babies and it's not. this is babies health that could be at risk because not everyone mixes the same. I know people who don't even boil the water. I didn't know you had to before so I assume they didn't know either. but to me it's alittle scary how different some of the instructions are. everyone should be on the same page. I feel like it's a science experiment. it shouldn't be like that. 
I mixed last night batch the way my mom learned in the class. I was worried because according to the glass measuring cup it's less than what's measured from the bottle. I didn't want my baby to be starving. but after I fed her she was so content and full she was so happy! and same with today. before she would seem to want more. probably because it was watered down. I felt like a bad mom last night when I found all this out.  but I didn't have the information  and was doing the best with the knowledge I had. I feel better today with what I learned last night. I hope this helps anyone else that formula feeds!