Yes, I saw you all the time in Cartier section~~
I bought two pairs of louboutin for my son, so I think I can help a bit.
It depends heavily on the shape of your feet. Whether it's sneaker or oxford, they are all
narrowly fitted but sneaker is (slightly) roomier than oxford.
If your feet is bony, skinny, low arc and narrow, then Louboutin may be true to size (or +1/2 size for comfort) for you.
If your feet is wide, thick, high arc, and with a good amount of fat under the skin, then you are looking at at least +1 size from your normal size.
I know the website always says the shoes fit true to size, that is true
only if your feet is just skin and bones. Otherwise you may have difficulty trying to shove your feet in the shoe.