Just to check a few things- are you running a knife or spatula around the edges, pressing it against the pan sides, before unmolding? And when you say pam, is it pam for baking or regular pan spray? I find the best release to come with either baker’s joy or shortening and wondra flour.
Also, the white velvet interior is fairly white, but because it’s made with butter it does have a bit of an off-white color compared to a white cake made with shortening (which lacks taste). As long as you didn’t get yolks in the batter or use butter with an unusually yellow color, I suspect you probably achieved the proper off-white color of the cake.
You can see it in a photo of the white lilac nostalgia cake (TCB) or the chocolate covered strawberry cake (RHC).