The tip isn’t too difficult. Just continue with the same technique but make it small on the end and and fillet it once you’ve lofted. You’ll see that I selected the first spline sketch so that I could make the two splines tangent, ensuring the faces are flat against one another.
The next part will depend on how much space you have to play with which is dependent on the curves you have before and after the parts join.
I’d start with selecting the end face, use the Offset Edge tool to create the inner part and then you’ll probably have to union on one end and maybe subtract from the other.