I am trying to learn surfacing, and I was hoping someone could help me figure out the next steps in doing surfacing on this box cutter.

I would think this would not be too difficult for those with a better handle on surfacing, but I am confused how to do the surface boundary or loft, when I don't really have the 3 orthographic splines set up, so it's obvious. Like, I am not sure if the front spline needs to be split into 2 entities.

The splines should be set up ok to be aligned with equal length (like if you need to do a projected curve), and I created a helper surface on the front spline. I can't seem to use the side sketch to get a usable guide curve or even make it pierced to the front or top spline.

Any advice is appreciated!  Thanks! (model attached)