Hi. I'm new here and was hoping someone could help out. Trying to create an inset on my model (inset for an user's finger). I've been using the loft cut feature using several ellipses on horizontal planes, but having a hard time getting it right. I've gotten it at times, but then I had to completely redo it when I changed some things on the model. Right now I have a split lines on where I want the inset. What is the best way of doing this or a better way so it'll easy to fix if adjustments are made? Thanks.

Sketch of what I'm trying to get.