I am really repeating what Kiwi has said but I have read that hard cheese contains much less lactose (hardly any?)and I have been making my own yoghurt fermenting it for 24 hours as all the lactose goes (not very technical I know
). I bought an EasiYo (£15 maybe cheaper in the US)a couple of months ago, its basicaly a large mouthed plastic flask with a container that fits inside to put the yoghurt in. I dont use the sachets you can buy I make the mix myself.
I put 4 cups milk in a pan and heat stirring to 82degC then leave to cool to 46 degC. Then add 1/4 cup probiotic yoghurt and mix. Then I put it in the yoghurt maker as per the EasiYo directions in the section I have pasted from http://www.greenlivingaustralia.com.au/yoghurt.html
A yoghurt maker will have directions on maintaining the heat. The only change required here is that in an EasiYo system for example, do not fill the external container so high with boiling water, as to have it come in direct contact with the yoghurt container as this may scald, and kill some culture. Just fill it to the level of the hole in the baffle, and this will give you the benefit of a heat reservoir, without risking scalding or killing the culture.
If you do not have a yoghurt maker, then place your jar in an esky and add warm water, but do not have very hot, or boiling water, in direct contact with the jar. You can also wrap your jar in a blanket, and place it in a warm place; on top of the hot water heater works well in my laundry.
To check if your yogurt is ready, press a spoon into the surface of the yoghurt and see if the impression of the spoon is left. If so, it is done.
Their temperatures are different I use the ones from my GAPS Internal Bliss cookbook. If you use raw milk or I think UHT you dont need to do the heating up first it is explained in the link.
You can also make yoghurt cheese but I havent tried this yet: put the yoghurt in a fine mesh cheescloth, tie the top around a wooden spoon and place over a bowl so that the liquid can drip into the bowl. Keep the bowl in the fridge for about 8hours depending on how thick you want it. It supposedly can be eaten as is, used to replace cream chesse or as adip/spread.
We have a large family gathering tomorrow (visiting relative from Canada) and I was going to do this to make a dip just didnt have the cheesecloth so it will have to wait until another day
I dont know for sure if I react to dairy but I haven't so far to the homemade yoghurt. I have been limiting cheese intake and so far have got away with eating cheese (hard) a couple of times a week.
I also don't have butter but make my own ghee instead using organic unsalted butter. Apparently you are less likely to react to it and it is cheaper than coconut oil for cooking I use it for savoury things.