Believe in the measure redken - if it says 32, then thats what it says. - you don't add 4 inches ala M & S and co.
It will obviously feel tighter - because it is tighter, the band should be firm but not uncomfortably so, it should not be able to ping more than a couple of inches away from your body. The band does most of the support.
It may even leave a mark when you take it off, this is not wrong as such, but similar to if you took off a tight pair of jeans, or the tops of your socks etc.
It will feel odd wearing it as well, as you are not used to those pressure points. a bit like when you wore your first bra.
But honestly try it, you will be very pleasantly surprised. I went from a 38 C to a 34 FF and was at that time a size 16. (to give an example of body size in relation to band size :) )
You also need to scoop any under arm escapee boobage and usher it up front where it needs to be.
I would suggest a trip to Bravisimo who measure this way - you need to make an appointment before you go