If you have the right sized boots but are getting Blisters, then the boots just need wearing in. To help you can put vaseline on the sore areas to help prevent rubbing. If it's pretty bad, try putting plasters on the contact points which are sore until the boots begin to mould to your feet. Im an athletic trainer at my school and we always have those for the Football players to use. Ideally you should gradually wear the boots more and more often until they are comfy and pain free! An Idea of why they are cutting only one of your feet is because every person has a foot that is bigger than the other one, even just slightly. Now dont run out and get a new size! Just have to break them in :) Hope That Helps!
Because are "FG" studs for a reason, you should never wear firm ground boots on astro-turf, its very dangarous.